Answer:
2C₆H₁₄ + 19O₂ → 12CO₂ + 14H₂O
α =2
β = 19
γ = 12
δ = 14
53.2moles of O₂
Explanation:
Proper equation of the reaction:
αC₆H₁₄ + βO₂ → γCO₂ + δH₂O
This is a combustion reaction for a hydrocarbon. For the combustion of a hydrocarbon, the combustion equation is given below:
CₓHₙ + (x + [tex]\frac{n}{4}[/tex])O₂ → xCO₂ + [tex]\frac{n}{2}[/tex]H₂O
From the given combustion equation, x = 6 and n = 14
Therefore:
β = x + [tex]\frac{n}{4}[/tex] = 6 + [tex]\frac{14}{4}[/tex] = 6 + 3.5 = 9[tex]\frac{1}{2}[/tex]
γ = 6
δ = [tex]\frac{n}{2}[/tex] = [tex]\frac{14}{2}[/tex] = 7
The complete reaction equation is therefore given as:
C₆H₁₄ + 9[tex]\frac{1}{2}[/tex]O₂ → 6CO₂ + 7H₂O
To express as whole number integers, we multiply the coefficients through by 2:
2C₆H₁₄ + 19O₂ → 12CO₂ + 14H₂O
Problem 2
From the reaction:
2 moles of hexane are required to completely react with 19 moles of O₂
∴ 5.6 moles of hexane would react with k moles of O₂
This gives: 5.6 x 19 = 2k
k = [tex]\frac{5.6 x 19}{2}[/tex]
k = 53.2moles of O₂
For the reaction shown, find the limiting reactant for each of the following initial amounts of reactants. 4Al(s)+3O2(g)→2Al2O3(s) A) 1 molAl, 1 mol O2 B) 4 molAl, 2.6 mol O2 C) 16 molAl, 13 mol O2 D) 7.4 molAl, 6.5 mol O2
Answer:
For A: Aluminium is the limiting reagent.
For B: Oxygen gas is the limiting reagent.
For C: Aluminium is the limiting reagent.
For D: Aluminium is the limiting reagent.
Explanation:
Limiting reagent is defined as the reagent which is present in less amount and it limits the formation of products.
Excess reagent is defined as the reagent which is present in large amount.
For the given chemical reaction:
[tex]4Al(s)+3O_2(g)\rightarrow 2Al_2O_3(s)[/tex]
For A: 1 mol Al, 1 mol [tex]O_2[/tex]By stoichiometry of the reaction:
4 moles of aluminium reacts with 3 moles of oxygen gas
So, 1 mole of aluminum will react with = [tex]\frac{3}{4}\times 1=0.75moles[/tex] of oxygen gas.
As, the given amount of oxygen gas is more than the required amount. Thus, it is considered as an excess reagent.
Hence, aluminium is the limiting reagent.
For B: 4 mol Al, 2.6 mol [tex]O_2[/tex]By stoichiometry of the reaction:
3 moles of oxygen gas reacts with 4 moles of aluminium
So, 2.6 moles of oxygen gas will react with = [tex]\frac{4}{3}\times 2.6=3.458moles[/tex] of aluminium.
As, the given amount of aluminium is more than the required amount. Thus, it is considered as an excess reagent.
Hence, oxygen gas is the limiting reagent.
For C: 16 mol Al, 13 mol [tex]O_2[/tex]By stoichiometry of the reaction:
4 moles of aluminium reacts with 3 moles of oxygen gas
So, 16 mole of aluminum will react with = [tex]\frac{3}{4}\times 16=12moles[/tex] of oxygen gas.
As, the given amount of oxygen gas is more than the required amount. Thus, it is considered as an excess reagent.
Hence, aluminium is the limiting reagent.
For D: 7.4 mol Al, 6.5 mol [tex]O_2[/tex]By stoichiometry of the reaction:
4 moles of aluminium reacts with 3 moles of oxygen gas
So, 7.4 mole of aluminum will react with = [tex]\frac{3}{4}\times 7.4=5.55moles[/tex] of oxygen gas.
As, the given amount of oxygen gas is more than the required amount. Thus, it is considered as an excess reagent.
Hence, aluminium is the limiting reagent.
Limiting reactant are defined as the reactant that is involved primarily in the reaction and formation of product depends on this reactant. the limiting reactant for the given equation are as follows:
A: Aluminium is the limiting reagent. B: Oxygen gas is the limiting reagent. C: Aluminium is the limiting reagent. D: Aluminium is the limiting reagent.Limiting reagent are those that limits the formation of products, whereas the reagent present in the excess amount are known as excess reagent.
For A:
For the given chemical reactions, limiting reagents are:
[tex]\text {4 Al}+ \text{3 O}_2\rightarrow\;\text{2Al}_2\text O_3[/tex]By applying the stereochemistry concept:
4 moles of Al reacts with 3 moles of oxygen.
1 mole of Al will react [tex]\dfrac {3}{4}\times 1&= 0.75[/tex] moles of oxygen.Hence, the given amount of oxygen is more than the required amount, it is an excess reagent and aluminum is limiting reagent.
For B:Similarly, in the chemical reaction, where 4 moles of aluminum react with 2.6 moles of oxygen, such that:
3 moles of oxygen reacts with 4 moles of aluminum.
so, 2.6 moles will react with [tex]\dfrac {3}{4}\times 2.6&= 3.458[/tex] moles of aluminum.The given amount of aluminium is more than the required amount, aluminum is considered as an excess reagent and oxygen gas is the limiting reagent.
For C:Also, 16 moles of aluminum reacts with 13 moles of oxygen.
4 moles of aluminum reacts with 3 moles of oxygen, such that:
16 moles of aluminum will react with [tex]\dfrac {3}{4}\times 16&= 12[/tex] moles of oxygen.Thus, oxygen is excess reagent and aluminum is limiting reagent.
For D:7.4 mol Aluminum reacts with 6.5 moles of oxygen, such that:
7.4 moles of aluminum will react with [tex]\dfrac {3}{4}\times 7.4 &= 5.55[/tex] moles of oxygen gas.Therefore, the aluminum is limiting reagent and oxygen is excess reagent.
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Magnesium hydroxide, the active ingredient in milk of magnesia, neutralizes stomach acid, primarily HCl, according to the reaction Mg(OH)2(aq)+2HCl(aq)→2H2O(l)+MgCl2(aq) What mass of HCl, in grams, is neutralized by a dose of milk of magnesia containing 3.26 g of Mg(OH)2? Express the mass in grams to three significant figures.
Answer:
Explanation:
For reaction stoichiometry problems like this, convert given data to moles and set up a ratio expression that relates to the balanced equation. That is ...
Given Rxn => Mg(OH)₂ + 2HCl => 2H₂O + MgCl₂
Given mass => 3.26g = (3.26g)/(58g/mol) = 0.056 mole Mg(OH)₂
If from equation 1 mole Mg(OH)₂ reacts with 2 moles HCl
then, 0.056 mole Mg(OH)₂ reacts with x moles HCl
Setting up ratio and proportion expression ...
=> (1 mole Mg(OH)₂) /(0.056 mole Mg(OH)₂) = (2 moles HCl)/x
=> x = [2(0.056)/(1)] mole HCl neutralized = 0.112mole HCl (36g/mol)
= 4.05 grams of HCl neutralized.
4.08 grams of HCl are neutralized by a dose of milk of magnesia containing 3.26 g of Mg(OH)₂.
Let's consider the neutralization reaction between HCl and Mg(OH)₂.
Mg(OH)₂(aq) + 2 HCl(aq) → 2 H₂O(l) + MgCl₂(aq)
First, we will convert 3.26 g of Mg(OH)₂ to moles using its molar mass (58.32 g/mol).
[tex]3.26 g \times \frac{1mol}{58.32g} = 0.0559 mol[/tex]
The molar ratio of Mg(OH)₂ to HCl is 1:2. The moles of HCl that react with 0.0559 moles of Mg(OH)₂ are:
[tex]0.0559 mol Mg(OH)_2 \times \frac{2molHCl}{1mol Mg(OH)_2} = 0.112molHCl[/tex]
Finally, we will convert 0.112 moles of HCl to grams using its molar mass (36.46 g/mol).
[tex]0.112 mol \times \frac{36.46g}{mol} = 4.08 g[/tex]
4.08 grams of HCl are neutralized by a dose of milk of magnesia containing 3.26 g of Mg(OH)₂.
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Question 2 The metal molybdenum becomes superconducting at temperatures below 0.90K. Calculate the temperature at which molybdenum becomes superconducting in degrees Celsius. Round your answer to 2 decimal places.
Answer:
Temperature at which molybdenum becomes superconducting is-272.25°C
Explanation:
Conductor are those hard substances which allows path of electric current through them. And super conductors are those hard substances which have resistance against the flow of electric current through them.
As given, molybdenum becomes superconducting at temperatures below 0.90 K.
Temperature in Kelvins can be converted in °C by relation:
T(°C)=273.15-T(K)
Molybdenum becomes superconducting in degrees Celsius.
T(°C)=273.15-0.90= -272.25 °C
Temperature at which molybdenum becomes superconducting is -272.25 °C
Classify each of these reactions. 2HBr(aq)+Ba(OH)2(aq)⟶2H2O(l)+BaBr2(aq) 2HBr(aq)+Ba(OH)2(aq)⟶2H2O(l)+BaBr2(aq) C2H4(g)+3O2(g)⟶2CO2(g)+2H2O(l) C2H4(g)+3O2(g)⟶2CO2(g)+2H2O(l) Cu(s)+FeCl2(aq)⟶Fe(s)+CuCl2(aq) Cu(s)+FeCl2(aq)⟶Fe(s)+CuCl2(aq) Na2S(aq)+2AgNO3(aq)⟶2NaNO3(aq)+Ag2S(s) Na2S(aq)+2AgNO3(aq)⟶2NaNO3(aq)+Ag2S(s)
1. Double replacement but no reaction
2. Double replacement but no reaction
3. Combustion
4. Combustion
5. Single replacement
6. Double replacement
I didn't solve the ones that are repeated! Hope it helped;)
Answer:
1. Double displacement.
2. Combustion.
3. Simple displacement.
4.Double displacement.
Explanation:
Hello,
1. [tex]2HBr(aq)+Ba(OH)_2(aq) -->2H_2O(l)+BaBr_2(aq)[/tex]
In this case, it is about a double displacement reaction since all the cations (H and Ba) and anions (Br and OH) are exchanged.
2. [tex]C_2H_4(g)+3O_2(g)-->2CO_2(g)+2H_2O(l)[/tex]
In this case, it is about the combustion of ethene.
3. [tex]Cu(s)+FeCl_2(aq)-->Fe(s)+CuCl_2(aq)[/tex]
In this case, it is about a simple displacement reaction since the iron (II) cations become solid iron and on the contrary for copper.
4. [tex]Na_2S(aq)+2AgNO_3(aq)-->2NaNO_3(aq)+Ag_2S(s)[/tex]
Finally, it is about a double displacement chemical reaction since the sodium and silver cations are exchanged with the sulfide and nitrate anions.
Best regards.
The Mond process produces pure nickel metal via the thermal decomposition of nickel tetracarbonyl: Ni(CO)4 (l) → Ni (s) + 4CO (g). What volume (L) of CO is formed from the complete decomposition of 444 g of Ni(CO)4 at 752 torr and 22.0 °C?
Answer: The volume of CO formed is 254.43 L.
Explanation:
To calculate the number of moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]
Given mass of [tex]Ni(CO)_4[/tex] = 444 g
Molar mass of [tex]Ni(CO)_4[/tex] = 170.73 g/mol
Putting values in above equation, we get:
[tex]\text{Moles of }Ni(CO)_4=\frac{444g}{170.73g/mol}=2.60mol[/tex]
For the given chemical reaction:
[tex]Ni(CO)_4(l)\rightarrow Ni(s)+4CO(g)[/tex]
By stoichiometry of the reaction:
1 mole of nickel tetracarbonyl produces 4 moles of carbon monoxide.
So, 2.60 moles of nickel tetracarbonyl will produce = [tex]\frac{4}{1}\times 2.60=10.4mol[/tex] of carbon monoxide.
Now, to calculate the volume of the gas, we use ideal gas equation, which is:
PV = nRT
where,
P = Pressure of the gas = 752 torr
V = Volume of the gas = ? L
n = Number of moles of gas = 10.4 mol
R = Gas constant = [tex]62.364\text{ L Torr }mol^{-1}K^{-1}[/tex]
T = Temperature of the gas = [tex]22^oC=(273+22)K=295K[/tex]
Putting values in above equation, we get:
[tex]752torr\times V=10.4mol\times 62.364\text{ L Torr }mol^{-1}K^{-1}\times 295K\\\\V=254.43L[/tex]
Hence, the volume of CO formed is 254.43 L.
The volume of CO gas formed from the complete decomposition of 444 g of Ni(CO)4 can be found using the ideal gas law.
Explanation:The given equation shows the thermal decomposition of nickel tetracarbonyl, Ni(CO)4: Ni(CO)4 (l) → Ni (s) + 4CO (g)
To find the volume of CO gas formed, we need to use the ideal gas law:
PV = nRT
Where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature in Kelvin.
We can use the given information to find the number of moles of CO, and then use the ideal gas law to find the volume. First, we need to convert the mass of Ni(CO)4 to moles using the molar mass:
Moles of Ni(CO)4 = mass of Ni(CO)4 / molar mass of Ni(CO)4
Next, we can use the stoichiometry of the balanced equation to relate the moles of Ni(CO)4 to moles of CO:
Moles of CO = moles of Ni(CO)4 × (4 moles of CO / 1 mole of Ni(CO)4)
Finally, we can use the ideal gas law to find the volume of CO:
V = (n × R × T) / P
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If the velocity profile of a fluid emerging from a control surface varies with surface area, the control volume form of the momentum equation can be used. (T/F)
Answer:
False
Explanation:
For different diameter pipes flow rate remains constant but velocity is different. (from continuity A1V1= A2V2). As area changes the velocity of fluid changes
A dextrose/saline aqueaout solution doctors commonly use to replace fluids in the body contains 1.75g/L NaCl and 40.0g/L dextrose. a) what is the molarity of all solutes in this solution? b) what is the osmotic pressure of the solution at 25 C. assume total dissociation of NaCL. Show work please!
Mixed molarity = 0.25 M
Osmotic pressure solution: 6.15 atm
Further explanationOsmotic pressure is the minimum pressure given to the solution so that there is no osmotic displacement from a more dilute solution to a more concentrated solution.
General formula:
[tex]\large{\boxed {\bold {\pi \: = \: M \: x \: R \: x \: T}}}[/tex]
π = osmotic pressure (atm)
M = solution concentration (mol / l)
R = constant = 0.08205 L atm mol-1 K-1
T = Temperature (Kelvin)
Mixing solution
To find the molarity of the mixed solution we can use the following formula:
Vc. Mc = V1.M1 + V2.M2
where
Mc =Mixed molarity
Vc = mixed volume
Mr. NaCl = 58.5
Mr. Dextrose = C₆H₁₂O₆ = 180
mole NaCl = gram / Mr
mole NaCl = 1.75 / 58.5 = 0.03
Dextrose mole = 40/180 = 0.22
Assuming 1 liter of solution
M mixture = mole NaCl + mole dextrose / 1 liter
M mixture = 0.03 + 0.22 / 1 L
M mix = 0.25 M
T = 25 + 273 = 298 K
The osmosis pressure of the solution becomes:
π = 0.25. 0.0825. 298 = 6.15 atm
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Answer detailsGrade: Senior High School
Subject: Chemistry
Chapter: Colligative property
Keywords: osmotic pressure, molarity, mole,dextrose, NaCl
Write a net ionic equation for the reaction that occurs when excess hydrochloric acid (aq) and potassium sulfite (aq) are combined. Note: Sulfites follow the same solubility trends as sulfates.
Answer: The net ionic equation for the given reaction is [tex]2H^+(aq.)+SO_3^{2-}(aq.)\rightarrow H_2O(l)+SO_2(g)[/tex]
Explanation:
Net ionic equation of any reaction does not include any spectator ions.
Spectator ions are the ions which do not get involved in a chemical equation. It is also defined as the ions that are found on both the sides of the chemical reaction when it is present in ionic form.
The chemical equation for the reaction of hydrochloric acid and potassium sulfite is given as:
[tex]2HCl(aq.)+K_2SO_3(aq.)\rightarrow 2KCl(aq.)+SO_2(g)+H_2O(l)[/tex]
Ionic form of the above equation follows:
[tex]2H^+(aq.)+2Cl^-(aq.)+2K^+(aq.)+SO_3^{2-}(aq.)\rightarrow 2K^+(aq.)+2Cl^-(aq.)+SO_2(g)+H_2O(l)[/tex]
As, potassium and chloride ions are present on both the sides of the reaction, thus, it will not be present in the net ionic equation.
The net ionic equation for the above reaction follows:
[tex]2H^+(aq.)+SO_3^{2-}(aq.)\rightarrow SO_2(g)+H_2O(l)[/tex]
Hence, the net ionic equation for the given reaction is written above.
The net ionic equation for the reaction between hydrochloric acid and potassium sulfite is H+ (aq)+ SO3^2- (aq) → H+ (aq) + SO3^2- (aq), following the solubility trends of sulfates and sulfites under standard conditions.
Explanation:The reaction between excess hydrochloric acid (HCl) and potassium sulfite (K2SO3) is a typical acid-base neutralization reaction. In the initial step, potassium sulfite dissociates into its ions in the aqueous solution:
K2SO3 (aq) → 2K+ (aq) + SO3^2- (aq)
Hydrochloric acid, being a strong acid, also dissociates completely:
HCl (aq) → H+ (aq) + Cl- (aq)
The hydrogen ion from the acid then reacts with the sulfite ion to form sulfuric acid and water, creating a net ionic equation :
2H+ (aq) + SO3^2- (aq) → H2SO3 (aq)
Because of the solubility trends of sulfates and sulfites under standard conditions, the sulfuric acid produced also dissociates into ions:
H2SO3 (aq) → 2H+ (aq) + SO3^2- (aq)
Therefore, the overall net ionic equation is:
H+ (aq)+ SO3^2- (aq) → H+ (aq) + SO3^2- (aq)
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Consider the neutralization reaction 2HNO3(aq)+Ba(OH)2(aq)⟶2H2O(l)+Ba(NO3)2(aq) 2HNO3(aq)+Ba(OH)2(aq)⟶2H2O(l)+Ba(NO3)2(aq) A 0.110 L0.110 L sample of an unknown HNO3HNO3 solution required 51.9 mL51.9 mL of 0.100 M Ba(OH)20.100 M Ba(OH)2 for complete neutralization. What is the concentration of the HNO3HNO3 solution? concentration:
Answer: The concentration of [tex]HNO_3[/tex] solution will be 0.094 M.
Explanation:
To calculate the concentration of acid, we use the equation given by neutralization reaction:
[tex]n_1M_1V_1=n_2M_2V_2[/tex]
where,
[tex]n_1,M_1\text{ and }V_1[/tex] are the n-factor, molarity and volume of acid which is [tex]HNO_3[/tex]
[tex]n_2,M_2\text{ and }V_2[/tex] are the n-factor, molarity and volume of base which is [tex]Ba(OH)_2[/tex]
We are given:
Conversion factor: 1L = 1000 mL
[tex]n_1=1\\M_1=?M\\V_1=0.110L=110mL\\n_2=2\\M_2=0.100M\\V_2=51.9mL[/tex]
Putting values in above equation, we get:
[tex]1\times M_1\times 110=2\times 0.100\times 51.9\\\\M_1=0.094M[/tex]
Hence, the concentration of [tex]HNO_3[/tex] solution will be 0.094 M.
The concentration of the HNO3 solution can be found by calculating the moles of Ba(OH)2 used in neutralization, which gives us the moles of HNO3 due to reaction stoichiometry. The HNO3 concentration (molarity) is then found by dividing its moles by its volume.
Explanation:In the given neutralization reaction, two moles of HNO3 react with one mole of Ba(OH)2. Given that 51.9 mL of 0.100 M Ba(OH)2 is used to completely neutralize the solution, the moles of Ba(OH)2 used can be obtained by using the formula Molarity (M) = Moles/Liter and converting the mL to L. The reaction stoichiometry implies that the moles of HNO3 must be twice that of Ba(OH)2.
Therefore, the total moles of HNO3 can be calculated by doubling the moles of Ba(OH)2. Divide these moles by the volume of the HNO3 solution (0.110 L) to find its molarity.
To summarize, the calculation process involves finding out the moles of Ba(OH)2 used, using this to find the moles of HNO3, and then dividing this by the volume of HNO3 solution to yield the molarity. Please carry out these calculations to get your final answer.
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In a constant‑pressure calorimeter, 70.0 mL of 0.350 M Ba(OH)2 was added to 70.0 mL of 0.700 M HCl. The reaction caused the temperature of the solution to rise from 22.32 ∘C to 27.09 ∘C. If the solution has the same density and specific heat as water ( 1.00 g/mL and 4.184J/g⋅K,) respectively), what is Δ???? for this reaction (per mole H2O produced)? Assume that the total volume is the sum of the individual volumes.
Answer:
ΔH = 57 Kj/mole H₂O
Explanation:
Answer:
ΔH/mol H₂O = 55346 J/mol H₂O =55.346 kJ/mol H₂O
Explanation:
The reaction that occurs in this case is:
Ba(OH)₂ + 2 HCl ----> BaCl₂ + 2 H₂O
The measurement and calculation of the amounts of heat exchanged by a system is called calorimetry. The equation that allows calculating these exchanges is:
Q=c*m*ΔT
where Q is the heat exchanged for a body of mass m, constituted by a substance whose specific heat is c, and ΔT is the temperature variation experienced.
In this case:
c=4.184 [tex]\frac{J}{g*C}[/tex] mass solution = mass Ba(OH)₂ + mass HClGiven that the solution has the same density as water (1.00 [tex]\frac{g}{mL}[/tex]) then the mass of Ba (OH)₂ and HCl can be calculated as:
[tex]mass Ba(OH)2=70 mL*\frac{1 g}{1 mL}[/tex]
mass Ba(OH)₂=70 g
[tex]mass HCl=70 mL*\frac{1 g}{1 mL}[/tex]
mass HCl=70 g
mass solution = 70 g of Ba(OH)₂ + 70 g of HCl
mass solution = 140 g
Another way to calculate the mass of the solution is:
The total volume is the sum of the individual volumes:
total volume= volume of Ba(OH)₂ + volume of HCl = 70 mL + 70 mL
total volume= 140 mL
Given that the solution has the same density as water (1.00 [tex]\frac{g}{mL}[/tex]) then
[tex]mass solution=140 mL*\frac{1 g}{1 mL}[/tex]
mass solution = 140 g
ΔT=28.70° C - 24.07 °C= 4.63° CThen
Q = 140 g* 4.184 [tex]\frac{J}{g*C}[/tex] *4.63° C =2712 J
By reaction stochetry (that is, by the relationships between the molecules or elements that make up the reactants and reaction products) 2 moles of HCl produce 2 moles of H2O.
Then
[tex]moles HCl=70 mL*\frac{1 L}{1000 mL} *\frac{0.700 g}{1 L}[/tex]
moles HCl=0.049
The rule of three or is a way of solving problems of proportionality between three known values and an unknown value, establishing a relationship of proportionality between all of them. That is, what is intended with it is to find the fourth term of a proportion knowing the other three. Remember that proportionality is a constant relationship or ratio between different magnitudes.
If the relationship between the magnitudes is direct, that is, when one magnitude increases, so does the other (or when one magnitude decreases, so does the other) , the direct rule of three must be applied. To solve a direct rule of three, the following formula must be followed:
a ⇒ b
c ⇒ x
So
[tex]x=\frac{c*b}{a}[/tex]
In this case: If 2 moles of H2O are formed if 2 moles of HCl react, how many moles of H2O will be formed if 0.049 moles of HCl react?
[tex]moles H2O=\frac{0.049 moles*2moles}{2 moles}[/tex]
moles H2O=0.049 moles
Now
ΔH/mol H₂O = [tex]\frac{2712 J}{0.049 mol H2O}[/tex]
ΔH/mol H₂O = 55346 J/mol H₂O =55.346 kJ/mol H₂O
Listed below are the amounts of mercury (in parts per million, or ppm) found in tuna sushi sampled at different stores. The sample mean is 0.836 ppm and the sample standard deviation is 0.253 ppm. Use technology to construct a 90% confidence interval estimate of the mean amount of mercury in the population.
Final answer:
To create a 90% confidence interval for the mean amount of mercury in tuna sushi, use the sample mean (0.836 ppm), sample standard deviation (0.253 ppm), and sample size to calculate the margin of error and apply it to the sample mean.
Explanation:
To construct a 90% confidence interval estimate of the mean amount of mercury in the population, you can use the sample mean (0.836 ppm) and the sample standard deviation (0.253 ppm) along with the sample size to calculate the margin of error. Then add and subtract this margin of error from the sample mean to find the confidence interval.
The formula for the confidence interval is:
Confidence Interval = Sample Mean ± (t * (Sample Standard Deviation / sqrt(Sample Size)))
You will need a t-score for the appropriate degree of freedom and desired confidence level, which you can find using statistical software or a t-distribution table. Once you have the t-score, you can calculate the margin of error and the confidence interval.
This method reflects the uncertainty inherent in estimating a population parameter from a sample statistic and assumes that the sample is representative of the population and that mercury levels are normally distributed.
Show how to convert the temperature 84.7° C to Kelvin. Please include all steps and label the final answer.
Answer:
The answer is 357.85 K.
Explanation:
In order to convert temperatures from degrees Celsius to degrees Kelvin, use the following formula:
temperature in degrees Kelvin = temperature in degrees Celsius + 273.15.
(Oftentimes, 273 is used instead of 273.15; it depends on the discretion of the teacher or student.)
The temperature given in degrees Celsius = 84.7° C
Therefore, the temperature in degrees Kelvin (K) = 84.7 + 273.15 = 357.85 K.
What keeps an inflated balloon from falling down?
Answer:
Helium
Explanation:
A deuteron, 21H, is the nucleus of a hydrogen isotope and consists of one proton and one neutron. The plasma of deuterons in a nuclear fusion reactor must be heated to about 3.02×108 K . What is the rms speed of the deuterons? Express your answer using two significant figures.
Answer:
[tex]1.9 \times 10^{6}\text{ m/s}[/tex]
Explanation:
[tex]v_{\text{rms}} = \sqrt{\dfrac{3RT}{M}[/tex]
Data:
T = 3.02 × 10⁸ K
M = 2.013 × 10⁻³ kg/mol
Calculation:
[tex]v_{\text{rms}} = \sqrt{\dfrac{3\times 8.314\text{ J}\cdot\text{K}^{-1} \text{mol}^{-1} \times 3.02 \times 10^{8} \text{ K}}{2.014 \times 10^{-3} \text{ kg}\cdot \text{mol}^{-1}}}\\\\\\=\sqrt{3.740\times 10^{12} \text{ (m/s)}^{2}} = 1.9 \times 10^{6}\text{ m/s}[/tex]
The thermal energy and the conservation of energy allows to find the average speed of the deuteron atoms is:
v = 1.9 10⁶ m / s
The thermal energy of a particle is given by the Boltzmann energy partition relation, which in three dimensions is:
E = [tex]\frac{3}{2}[/tex] kT
Energy kinetic s the energy of movement and its expression is:
K = ½ m v²
They indicate that the temperature of the plasma is T = 3.02 10⁸ K.
If there are no losses, the energy is conserved.
K = E
½ m v² = [tex]\frac{3}{2}[/tex] kT
v = [tex]\sqrt{\frac{3 kT}{m} }[/tex]
[tex]\frac{1.66 \ 10^{-27} kg}{1 u}[/tex]
The mass of deuteron is m = 2.013 u
Let's reduce to kg
m = 2.013 u ( [tex]\frac{1.66 \ 10^{-27} kg}{1 uy}[/tex])
m = 3.5358 10⁻²⁷ kg
We take the mass of a deuterium to 1 mole, multiplying by Avogador's number.
m = 3.5358 10⁻²⁷ 6.022 10²³
m = 2.129 10⁻³ kg / mol
We calculate
v = [tex]\sqrt{ \frac{3 \ 8.314 \ 3.02 \ 10^8 }{2.129 \ 10^{-3} } }[/tex]
v = [tex]\sqrt{3.538 \ 10^{12}}[/tex]
v = 1.88 10⁶ m / s
They ask for the result with two significant figures.
v = 1.9 10⁶ m / s
In conclusion using thermal energy and conservation of energy we can find the average speed of deuteron atoms is:
v = 1.9 10⁶ m / s
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A particular radioactive nuclide has a half-life of 1000 years. What percentage of an initial population of this nuclide has decayed after 3500 years?
Answer:
91.16% has decayed & 8.84% remains
Explanation:
A = A₀e⁻ᵏᵗ => ln(A/A₀) = ln(e⁻ᵏᵗ) => lnA - lnA₀ = -kt => lnA = lnA₀ - kt
Rate Constant (k) = 0.693/half-life = 0.693/10³yrs = 6.93 x 10ˉ⁴yrsˉ¹
Time (t) = 1000yrs
A = fraction of nuclide remaining after 1000yrs
A₀ = original amount of nuclide = 1.00 (= 100%)
lnA = lnA₀ - kt
lnA = ln(1) – (6.93 x 10ˉ⁴yrsˉ¹)(3500yrs) = -2.426
A = eˉ²∙⁴²⁶ = 0.0884 = fraction of nuclide remaining after 3500 years
Amount of nuclide decayed = 1 – 0.0884 = 0.9116 or 91.16% has decayed.
Consider the reaction of A(g) + B(g) + C(g) => D(g) for which the following data were obtained:
Experiment Initial [A], mol/L Initial [B], mol/L Initial [C], mol/L Initial rate, mol/L.s
1 0.0500 0.0500 0.0100 6.25 x 10^-3
2 0.100 0.0500 0.0100 2.50 x 10^-2
3 0.100 0.100 0.0100 1.00 x 10^-1
4 0.0500 0.0500 0.0200 6.25 x 10^-3
What is the rate law for the reaction?
Answer:
[tex]r = k [A]^{2}[B]^{2}[/tex]
Explanation:
A + B + C ⟶ D
[tex]\text{The rate law is } r = k [A]^{m}[B]^{n}[C]^{o}[/tex]
Our problem is to determine the values of m, n, and o.
We use the method of initial rates to determine the order of reaction with respect to a component.
(a) Order with respect to A
We must find a pair of experiments in which [A] changes, but [B] and C do not.
They would be Experiments 1 and 2.
[B] and [C] are constant, so only [A] is changing.
[tex]\begin{array}{rcl}\dfrac{r_{2}}{r_{1}} & = & \dfrac{ k[A]_{2}^{m}}{ k[A]_{1}^{m}}\\\\\dfrac{2.50\times 10^{-2}}{6.25\times 10^{-3}} & = & \dfrac{0.100^{m}}{0.0500^{m}}\\\\4.00 & = & 2.00^{m}\\m & = & \mathbf{2}\\\end{array}\\\text{The reaction is 2nd order with respect to A}[/tex]
(b) Order with respect to B
We must find a pair of experiments in which [B] changes, but [A] and [C] do not. There are none.
They would be Experiments 2 and 3.
[A] and [C] are constant, so only [B] is changing.
[tex]\begin{array}{rcl}\dfrac{r_{3}}{r_{2}} & = & \dfrac{ k[B]_{3}^{n}}{ k[B]_{2}^{n}}\\\\\dfrac{1.00\times 10^{-1}}{2.50\times 10^{-2}} & = & \dfrac{0.100^{n}}{0.0500^{n}}\\\\4.00 & = & 2.00^{n}\\n & = & \mathbf{2}\\\end{array}\\\text{The reaction is 2nd order with respect to B}[/tex]
(c) Order with respect to C
We must find a pair of experiments in which [C] changes, but [A] and [B] do not.
They would be Experiments 1 and 4.
[A] and [B] are constant, so only [C] is changing.
[tex]\begin{array}{rcl}\dfrac{r_{4}}{r_{1}} & = & \dfrac{ k[C]_{4}^{o}}{ k[C]_{1}^{o}}\\\\\dfrac{6.25\times 10^{-3}}{6.25\times 10^{-3}} & = & \dfrac{0.0200^{o}}{0.0100^{o}}\\\\1.00 & = & 2.00^{o}\\o & = & \mathbf{0}\\\end{array}\\\text{The reaction is zero order with respect to C.}\\\text{The rate law is } r = k [A]^{2}[B]^{2}[/tex]
The rate law for the given reaction is determined to be rate = k[A]^2[B]^2[C]^0, based on careful comparisons of the relationship between initial concentrations of reactants [A], [B], [C] and the observed initial reaction rates in different experiments. The reaction is found to be second order in [A] and [B], and zero order in [C].
Explanation:The rate law for the given chemical reaction can be derived by comparing the changes in the experimentally determined initial rates with changes in the initial concentrations of the reactants [A], [B], and [C]. It's important to note here that the rate law shows how the rate of a reaction depends on the concentration of its reactants.
Looking at Experiments 1 and 2, we observe that the initial concentration of [A] has doubled (from 0.0500 mol/L to 0.100 mol/L), while the initial concentrations of [B] and [C] remain constant. The initial reaction rate quadruples, which suggests that the reaction is second order with respect to [A].
Comparing Experiments 2 and 3, the initial concentration of [B] doubles (from 0.0500 mol/L to 0.100 mol/L), while the concentrations of [A] and [C] remain constant. The rate quadruples, which shows that the reaction order is also second in [B].
Now comparing Experiments 1 and 4, where [C] doubles and [A] and [B] are kept constant, the rate remains unchanged. This suggests the reaction order is zero in [C].
Adding these together, we conclude that the rate law is rate = k[A]^2[B]^2[C]^0, where k is the rate constant.
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Which buffer would be better able to hold a steady pH on the addition of strong acid, buffer 1 or buffer 2? Explain. Buffer 1: a solution containing 0.10 M NH4Cl and 1 M NH3. Buffer 2: a solution containing 1 M NH4Cl and 0.10 M NH3
Answer:
Buffer 1.
Explanation:
Ammonia is a weak base. It acts like a Bronsted-Lowry Base when it reacts with hydrogen ions.
[tex]\rm NH_3\; (aq) + H^{+}\; (aq) \to {NH_4}^{+}\; (aq)[/tex].
[tex]\rm NH_3[/tex] gains one hydrogen ion to produce the ammonium ion [tex]\rm {NH_4}^{+}[/tex]. In other words, [tex]\rm {NH_4}^{+}[/tex] is the conjugate acid of the weak base [tex]\rm NH_3[/tex].
Both buffer 1 and 2 include
the weak base ammonia [tex]\rm NH_3[/tex], andthe conjugate acid of the weak base [tex]\rm {NH_4}^{+}[/tex].The ammonia [tex]\rm NH_3[/tex] in the solution will react with hydrogen ions as they are added to the solution:
[tex]\rm NH_3\; (aq) + H^{+}\; (aq) \to {NH_4}^{+}\; (aq)[/tex].
There are more [tex]\rm NH_3[/tex] in the buffer 1 than in buffer 2. It will take more strong acid to react with the majority of [tex]\rm NH_3[/tex] in the solution. Conversely, the pH of buffer 1 will be more steady than that in buffer 2 when the same amount of acid has been added.
How is the name of each element in the periodic table represented?
O
A. One or two letters are used to represent the name of each
element.
O
B. Letters are assigned to each element by the scientist who
discovered it.
O
C. Letters are given to represent each element based on when it was
discovered.
O
D. The first two letters of the element's name are used for the table.
Answer:
A. One or two letters are used to represent the name of each element
APEX
One or two letters are used to represent the name of each
element
The name of each element in the periodic table is symbolized by one or two letters.
There are different ways of achieving this. Sometimes;
The first letter of the name of the element is used to represent it, for example, hydrogen = HThe first two letters are sometimes used, for example, Calcium CaThe Latin name is also used for example Gold is Aurum and is represented as Au.These are some of the ways of symbolizing the name of each element.
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Nitrogen dioxide reacts with water to form nitric acid and nitrogen monoxide according to the equation: 3NO2(g)+H2O(l)→2HNO3(l)+NO(g) Part A Suppose that 4.2 mol NO2 and 0.50 mol H2O combine and react completely. Which reactant is in excess? Express your answer as a chemical formula. nothing
Final answer:
To determine which reactant is in excess, compare the number of moles of each reactant with the stoichiometric ratio in the balanced equation. In this case, NO2 is in excess.
Explanation:
To determine which reactant is in excess, we need to compare the number of moles of each reactant with the stoichiometric ratio in the balanced equation.
The balanced equation is:
3NO2(g) + H2O(l) -> 2HNO3(l) + NO(g)
According to the equation, the ratio of NO2 to H2O is 3:1. So, for every 3 moles of NO2, we need 1 mole of H2O.
Given that there are 4.2 mol of NO2 and 0.50 mol of H2O, we can calculate the mole ratio of NO2 to H2O:
4.2 mol NO2 / 3 mol NO2 = 1.4 mol NO2
0.50 mol H2O / 1 mol H2O = 0.50 mol H2O
From the calculations, it is clear that the amount of NO2 is more than the required amount based on the stoichiometric ratio. Therefore, NO2 is in excess.
Which of the following statements about acidic water is true? a. Acid has no effect on the H,O molecules. b. The solution contains a larger number of OH ions than H,O ions. c. The solution contains a larger number of H,O ions than QH ions. d. The solution contains an equal number of H,O ions and OH ions. none of the above e.
Answer:
C
Explanation:
Hydronium (H₃O+) is the same as H+ (aq) because of the same net charge. The acidic property of a solvent or solution is governed the amount of H+ ion in it. The higher the H+ ions the lower the pH. In pure water H₃O+ and OH- are in equal amount. More of OH- ions turn the solution basic.
Determine the percent sulfuric acid by mass of a 1.61 m aqueous solution of H2SO4. %
Answer:
Wt%H₂SO₄ = 10.2% (w/w)
Explanation:
1.61 molal H₂SO₄ = 1.61 mole H₂SO₄/Kg Solvent = 1.61 mole(98 g/mole)/Kg Solvent = 113.68 g H₂SO₄/Kg Solvent
Solution weight = 1000 g solvent + 113.68 g solute = 1113.68 g Solution
Wt%H₂SO₄ = (113.68 g/1113.68g)100% = 10.2% (w/w)
The percentage of sulfuric acid = 10.2% (w/w)
Given:
Molality of solution = 1.61m
Molality:It is a measure of the number of moles of solute in a solution corresponding to 1 kg or 1000 g of solvent.
1.61 molal H₂SO₄ = 1.61 mole H₂SO₄/Kg Solvent
= 1.61 mole(98 g/mole)/Kg Solvent = 113.68 g H₂SO₄/Kg Solvent
Solution is made up of solute and solvent. Thus,
Solution weight = 1000 g solvent + 113.68 g solute = 1113.68 g Solution
[tex]Wt\% \text{ of } H_2SO_4 = \frac{113.68 g}{1113.68g}*100\% = 10.2\% (w/w)[/tex]
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The initial concentration of A in the first-order reaction 4A→4B+C is 0.933 mol L−1. Given that the rate constant is 0.310 s−1, what is the half-life of the reaction in seconds? Remember to use correct significant figures in your answer (round your answer to the nearest hundredth). Do not include units in your response.
Answer: The half-life of the reaction in 2.24 seconds.
Explanation:
We are given a reaction which follows first order kinetics.
The formula used to calculate the half -life of the reaction for first order kinetics follows:
[tex]t_{1/2}=\frac{0.693}{k}[/tex]
where,
[tex]t_{1/2}[/tex] = half-life of the reaction
k = rate constant of the reaction = [tex]0.310s^{-1}[/tex]
Putting values in above equation, we get:
[tex]t_{1/2}=\frac{0.693}{0.310s^{-1}}\\\\t_{1/2}=2.235sec\approx 2.24sec[/tex]
The rule which is applied for multiplication and division problems is that the least number of significant figures in any number of a problem will determine the number of significant figures in the solution.
In the problem, the least precise significant figures are 3. Thus, the answer will also have 3 significant figures.
Hence, the half-life of the reaction in 2.24 seconds.
Both 1,2−dihydronaphthalene and 1,4−dihydronaphthalene may be selectively hydrogenated to 1,2,3,4−tetrahydronaphthalene. One of these isomers has a heat of hydrogenation of 101 kJ/mol (24.1 kcal/mol), and the heat of hydrogenation of the other is 113 kJ/mol (27.1 kcal/mol). Match the heat of hydrogenation with the appropriate dihydronaphthalene.
Answer:
1,4-dihydro = 113 kJ·mol⁻¹
1,2-dihydro = 101 kJ·mol⁻¹
Explanation:
In 1,4-dihydronaphthalene, the 2,3-double bond is isolated from the benzene ring.
In 1,2-dihydronaphthalene, the 3,4-double bond is conjugated with the benzene ring.
Thus, 1,2-dihydronaphthalene is partially stabilized by resonance interactions between the ring and the double bond (think, styrene).
1,2-Dihydronaphthalene is at a lower energy level because of this stabilization.
The heat of hydrogenation of 1,2-dihydronaphthalene is therefore less than that of the 1,4-isomer when each is hydrogenated to the common product, 1,2,3,4-tetrahydronaphthalene.
Write a balanced equation for the combination reaction described, using the smallest possible integer coefficients. When diphosphorus pentoxide combines with water , phosphoric acid is formed.
Answer:
P₂O₅ + 3H₂O => 2H₃PO₄
Explanation:
Nothing to explain.
When 0.625 g Mn is combined with enough hydrochloric acid to make 100.0 mL of solution in a coffee-cup calorimeter, all of the Mn reacts, raising the temperature of the solution from 23.5 °C to 28.8 °C. Find ΔHrxn for the reaction as written. (Assume that the specific heat capacity of the
Answer:
[tex]\boxed{\text{-194 kJ/mol}}[/tex]
Explanation:
Mn + 2HCl ⟶ MnCl₂ + H₂
There are two energy flows in this reaction.
[tex]\begin{array}{cccl}\text{Heat from reaction} & + &\text{Heat absorbed by water} & = 0\\q_{1} & + & q_{2} & =0\\n\Delta_{r}H & + & mC\Delta T & =0\\\end{array}[/tex]
Data:
Mass of Mn = 0.625 g
V = 100.0 mL
T₁ = 23.5 °C
T₂ = 28.8 °C
Calculations:
(a) Moles of Mn
[tex]n = \text{0.625 g Mn} \times \dfrac{\text{1 mol Mn }}{\text{54.94 g Mn}} = \text{0.011 38 mol Mn}[/tex]
(b) Mass of solution
[tex]m = \text{100.0 mL} \times \dfrac{\text{1.00 g}}{\text{1 mL}} = \text{100.0 g}[/tex]
(c) ΔT
ΔT = T₂ - T₁ = 28.8 °C – 23.5 °C = 5.3 °C
(d) q₁
[tex]q_{1} = \text{0.011 38 mol Mn} \times \Delta_{r}H = 0.01138 \Delta_{r}H \text{ mol}[/tex]
(e) q₂
q₂ = 100.0 × 4.184 × 5.3 = 2220 J
(f) ΔH
[tex]\begin{array}{rcl}0.01138 \Delta_{r}H + 2220 & = & 0\\0.01138 \Delta_{r}H & = & -2220\\\\\Delta_{r}H & = & \dfrac{-2220}{0.01138}\\\\ & = & \text{-194000 J/mol}\\ & = & \boxed{\textbf{-194 kJ/mol}}\\\end{array}\\\\[/tex]
The ΔHrxn for the reaction as written is -201.4 KJ/mol.
From the information provided in the question;
Mass of Mn = 0.625 g
Volume of solution = 100.0 mL
Initial temperature = 23.5 °C
Final temperature = 28.8 °C
Now;
The equation of the reaction is;
Mn(s) + 2HCl(aq) ------> MnCl2(aq) + H2(g)
Number of moles of Mn = 0.625 g /55 g/mol = 0.011 moles
Temperature rise = Final temperature - Initial temperature = 28.8 °C - 23.5 °C = 5.3 °C
Mass of the solution = Density of solution × volume of solution = 1.00 g/mL × 100.0 mL = 100 g
From the formula;
ΔHrxn =- mcθ
ΔHrxn is negative because heat is evolved.
m = mass of solution
c = specific heat capacity of the solution
θ= temperature rise
ΔHrxn = mcθ/number of moles
ΔHrxn =-(100 g × 4.18 J/g∘C × 5.3 °C)/0.011 moles
ΔHrxn = -201.4 KJ/mol
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When 0.620 g Mn is combined with enough hydrochloric acid to make 100.0 mL of solution in a coffee-cup calorimeter, all of the Mn reacts, raising the temperature of the solution from 23.1 ∘C to 28.9 ∘C. Find ΔHrxn for the reaction as written. (Assume that the specific heat capacity of the solution is 4.18 J/g∘C and the density is 1.00 g/mL.)
The student is now told that the four solids, in no particular order, are barium chloride (BaCl2), sugar (C6H12O6), butanoic acid (C3H7COOH), and sodium bromide (NaBr). Assuming that conductivity is correlated to the number of ions in solution, rank the four substances based on how well a 0.20 M solution in water will conduct electricity.
Answer:
Explanation:
Out of those choices, the chemical that ionizes the most is NaBr. It is like table salt (NaCl) in its properties. Solutbility 121 grams in 100 mL
You might think "Well if NaBr is such a good conductor, maybe a Metal combined with a non metal is the key and BaCl2 should be next." And in this case you would be right. 36 grams will dissolve in 100 mL
C3H7COOH is an acid and it is soluble in water. It is an acid and the last H splits off. It is not quite as good as the top two, but good enough all the same.
Sugar is probably the least soluble but it does form a suspension. It would be at the bottom of the last.
Answer:
The order of conductivities is: Sugar < Butanoic acid < Sodium bromide < Barium chloride
Explanation:
The conductivity of a solution is related to the concentration of ions. The higher the concentration of ions, the higher the conductivity.
Barium chloride is a strong electrolyte, according to the following equation.
BaCl₂(aq) ⇒ Ba²⁺(aq) + 2 Cl⁻(aq)
Each mole of BaCl₂ produces 3 moles of ions. Thus, if the solution is 0.20 M BaCl₂, it will be 0.60 M in ions.
Sugar (C₆H₁₂O₆) is a non-electrolyte. Thus, the concentration of ions will be zero.
Butanoic acid is a weak electrolyte, according to the following equation.
C₃H₇COOH(aq) ⇄ C₃H₇COO⁻(aq) + H⁺(aq)
Due to its weak nature, the concentration of ions will be lower than 0.20 M.
Sodium bromide is a strong electrolyte, according to the following equation.
NaBr(aq) ⇒ Na⁺(aq) + Br⁻(aq)
Each mole of NaBr produces 2 moles of ions. Thus, if the solution is 0.20 M BaCl₂, it will be 0.40 M in ions.
The order of conductivities is: Sugar < Butanoic acid < Sodium bromide < Barium chloride
Calculate q, w, and ? U for the reversible, isothermal compression of 10 mol of ideal gas from 1 to 10 atm at a constant temperature of 0°C.
Answer : The value of q, w and U for the reversible, isothermal compression are, -52271.69 J, 52271.69 J and 0 J respectively.
Explanation : Given,
Moles of gas = 10 mole
Initial pressure of gas = 1 atm
Final pressure of the gas = 10 atm
Temperature of the gas = [tex]0^oC=273+0=273K[/tex]
According to the question, this is the case of isothermal reversible compression of gas.
As per first law of thermodynamic,
[tex]\Delta U=q+w[/tex]
where,
[tex]\Delta U[/tex] = internal energy
q = heat
w = work done
As we know that, the term internal energy is the depend on the temperature and the process is isothermal that means at constant temperature.
So, at constant temperature the internal energy is equal to zero.
The expression used for work done will be,
[tex]w=-2.303nRT\log (\frac{P_1}{P_2})[/tex]
where,
w = work done on the gas
n = number of moles of gas
R = gas constant = 8.314 J/mole K
T = temperature of gas
n = moles of the gas
[tex]P_1[/tex] = initial pressure of gas
[tex]P_2[/tex] = final pressure of gas
Now put all the given values in the above formula, we get the work done.
[tex]w=-2.303\times 10mole\times 8.314J/moleK\times 273K\times \log (\frac{1atm}{10atm})[/tex]
[tex]w=52271.69J[/tex]
And we know that, the heat is equal to the work done with opposite sign convention.
So, [tex]q=-52271.69J[/tex]
Therefore, the value of q, w and U for the reversible, isothermal compression are, -52271.69 J, 52271.69 J and 0 J respectively.
Calculate the standard enthalpy of formation of liquid methanol, CH3OH(l), using the following information: C(graphite) + O2 LaTeX: \longrightarrow ⟶ CO2(g) LaTeX: \Delta Δ H° = –393.5 kJ/mol H2(g) + O2 LaTeX: \longrightarrow ⟶ H2O(l) LaTeX: \Delta Δ H° = –285.8 kJ/mol CH3OH(l) + O2(g) LaTeX: \longrightarrow ⟶ CO2(g) + 2H2O(l) LaTeX: \Delta Δ H° = –726.4 kJ/mol
Answer:
-238.54 kJ/mol.
Explanation:
We need to calculate the standard enthalpy of formation of liquid methanol, CH₃OH(l) that has the equation:C(graphite) + 2H₂(g) + ½ O₂(g) → CH3OH(l) ΔHf° = ? ?? kJ/mol.
using the information of the three equations:(1) C(graphite) + O₂(g) → CO₂(g), ΔHf₁° = -393.5 kJ/mol .
(2) H2(g) + ½ O₂(g) → H₂O(l), ΔHf₂° = -285.8 kJ/mol .
(3) CH₃OH(l) + 3/2 O₂(g) → CO₂(g) + 2H₂O(l), ΔH₃° = -726.56 kJ/mol .
We rearranging and add equations (1, 2, and 3) in such a way as to end up with the needed equation: equation (1) be as it is:(1) C(graphite) + O₂(g) → CO₂(g), ΔHf₁° = -393.5 kJ/mol .
equation (2) should be multiplied by (2) and also the value of ΔHf₂°:
(2) 2H2(g) + O₂(g) → 2H₂O(l), ΔHf₂° = 2x(-285.8 kJ/mol ).
equation (3) should be reversed and also the value of ΔH₃° should be multiplied by (-1):
(3) CO₂(g) + 2H₂O(l) → CH₃OH(l) + 3/2 O₂(g), ΔH₃° = 726.56 kJ/mol .
By summing the modified equations, we can get the needed equation and so:
The standard enthalpy of formation of liquid methanol, CH₃OH(l) = ΔHf₁° + 2(ΔHf₂°) - ΔH₃° = (-393.5 kJ/mol ) + 2(-285.8 kJ/mol ) - (- 726.56 kJ/mol) = -238.54 kJ/mol.
The standard enthalpy change of formation of liquid methanol, CH3OH(l), is calculated by manipulating and summing the reactions provided, considering the rules of Hess's law. The resulting ΔH° of the methanol formation from its elements is +976.0 kJ/mol.
Explanation:To calculate the standard enthalpy of formation ΔH° of liquid methanol, CH3OH(l), we will use the concept of Hess's law and the provided chemical equations. Hess's law states that the enthalpy change of a reaction depends only on the initial and final states, not on the pathway or steps taken to achieve the conversion.
The standard enthalpy formation reaction is defined as the formation of 1 mol of a compound from its elemental forms under standard state conditions. For methanol, the reaction would be: C(graphite) + 2H2(g) + 1/2O2 ⟶ CH3OH(l)
None of the provided reactions exactly match this equation. However, their combination, while keeping in mind the stoichiometry, gives the desired reaction. Note that as we know enthalpy is a state function, we could 'add' or 'subtract' reactions to get the desired one.
The reverse of the CO2 formation reaction is: CO2(g) ⟶ C(graphite) + O2, ΔH° = +393.5 kJ/mol
The reaction for the formation of 2 mol of H2O needs to be halved: 1/2H2(g) + 1/2O2 ⟶ 1H2O(l), ΔH° = -285.8 kJ/mol/2 = -142.9 kJ/mol
The combustion of methanol reaction needs to be reversed: CO2(g) + 2H2O(l) ⟶ CH3OH(l) + O2(g), ΔH° = +726.4 kJ/mol
Adding these revised equations together gives the desired equation for the formation of methanol from its elements and the ΔH formation is the sum of the ΔH of these revised reactions δH°(formation of CH3OH) = +393.5 kJ/mol - 142.9 kJ/mol + 726.4 kJ/mol = +976. Omega kJ/mol.
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How many grams of dry NH4Cl need to be added to 1.90 L of a 0.500 M solution of ammonia, NH3, to prepare a buffer solution that has a pH of 8.72? Kb for ammonia is 1.8×10−5.
Answer : The mass of dry [tex]NH_4Cl[/tex] needed are, 174.196 grams.
Explanation :
First we have to calculate the pOH of the solution.
[tex]pH+pOH=14[/tex]
[tex]pOH=14-pOH\\\\pOH=14-8.72\\\\pOH=5.28[/tex]
Now we have to calculate the [tex]pK_b[/tex].
[tex]pK_b=-\log K_b[/tex]
[tex]pK_b=-\log (1.8\times 10^{-5})[/tex]
[tex]pK_b=4.745[/tex]
Now we have to calculate the concentration of base, [tex]NH_4Cl[/tex].
Using Henderson Hesselbach equation :
[tex]pOH=pKb+\log \frac{[Salt]}{[Base]}[/tex]
[tex]pOH=pKb+\log \frac{[NH_4Cl]}{[NH_3]}[/tex]
Now put all the given values in this equation, we get :
[tex]5.28=4.745+\log \frac{[NH_4Cl]}{0.500}[/tex]
[tex][NH_4Cl]=1.714M[/tex]
Now we have to calculate the mass of [tex]NH_4Cl[/tex].
Formula used :
[tex]Molarity=\frac{\text{Moles of }NH_4Cl}{\text{Volume of solution}}[/tex]
[tex]Molarity=\frac{\text{Mass of }NH_4Cl}{\text{Molar mass of }NH_4Cl\times \text{Volume of solution}}[/tex]
Now put all the given values in this formula, we get:
[tex]1.714M=\frac{\text{Mass of }NH_4Cl}{53.49\times 1.90L}[/tex]
[tex]\text{Mass of }NH_4Cl=174.196g[/tex]
Therefore, the mass of dry [tex]NH_4Cl[/tex] needed are, 174.196 grams.
The pH has been the hydrogen ion concentration and pOH is the hydroxide ion concentration. The mass of ammonium chloride in the solution is 174.196 grams.
What is Kb?The Kb is the base dissociation constant for the compound.
The pH of the solution is 8.72, the pOH of the solution is given as:
[tex]\rm pH=14-pOH\\8.72=14-pOH\\pOH=5.28[/tex]
The pOH of the given solution is 5.28. The concentration of ammonium chloride salt in the solution from pOH can be given as:
[tex]\rm pOH=pKb\;+\;log\dfrac{salt}{acid}[/tex]
The pKb has been given as the logarithmic value of Kb. The concentration of ammonia is 0.5 M. Substituting the values for the concentration of ammonium chloride salt as:
[tex]\rm 5.28=log\;1.8\;\times\;10^{-5}\;+\;log\dfrac{NH_4Cl}{0.5}\\\\ 5.28=4.745\;+\;log\dfrac{NH_4Cl}{0.5}\\\\NH_4Cl=1.714\;M[/tex]
The concentration of ammonium chloride salt is 1.714 M. The volume of the solution is 1.90 L. The molar mass of the compound is 53.49 g/mol.
Substituting the values for the mass of ammonium chloride as:
[tex]\rm Molarity=\dfrac{mass}{molar\;mass\;\times\;volume} \\\\1.714\;M=\dfrac{mass}{53.49\;g/mol\;\times\;1.90\;L}\\\\ Mass=174.196\;g[/tex]
The mass of ammonium chloride added to the solution is 174.196 grams.
Learn more about base dissociation constant, here:
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If a solution containing 80.701 g80.701 g of mercury(II) perchlorate is allowed to react completely with a solution containing 12.026 g12.026 g of sodium sulfide, how many grams of solid precipitate will form? precipitate: gg How many grams of the reactant in excess will remain after the reaction? excess reactant:
Answer: The excess reagent for the given chemical reaction is mercury (II) perchlorate and the amount left after the completion of reaction is 0.048 moles. The amount of mercury sulfide formed in the reaction is 35.82 grams.
Explanation:
To calculate the number of moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ....(1)
For sodium sulfide:Given mass of sodium sulfide = 12.026 g
Molar mass of sodium sulfide = 78.045 g/mol
Putting values in above equation, we get:
[tex]\text{Moles of sodium sulfide}=\frac{12.026g}{78.045g/mol}=0.154mol[/tex]
For mercury (II) perchlorate:Given mass of mercury (II) perchlorate = 80.701 g
Molar mass of mercury (II) perchlorate = 399.49 g/mol
Putting values in above equation, we get:
[tex]\text{Moles of mercury (II) perchlorate}=\frac{80.701g}{399.49g/mol}=0.202mol[/tex]
For the given chemical equation:
[tex]Hg(ClO_4)_2(aq.)+Na_2S(aq.)\rightarrow HgS(s)+2NaClO_4(aq.)[/tex]
Here, the solid precipitate is mercury sulfide.
By Stoichiometry of the reaction:
1 mole of sodium sulfide reacts with 1 mole of mercury (II) perchlorate.
So, 0.154 moles of sodium sulfide will react with = [tex]\frac{1}{1}\times 0.154=0.154moles[/tex] of mercury (II) perchlorate
As, given amount of mercury (II) perchlorate is more than the required amount. So, it is considered as an excess reagent.
Thus, sodium sulfide is considered as a limiting reagent because it limits the formation of product.
Amount of excess reagent (mercury (II) perchlorate) left = 0.202 - 0.154 = 0.048 molesBy Stoichiometry of the reaction:
1 mole of sodium sulfide reacts with 1 mole of mercury sulfide.
So, 0.154 moles of sodium sulfide will react with = [tex]\frac{1}{1}\times 0.154=0.154moles[/tex] of mercury sulfide.
Now, calculating the mass of mercury sulfide from equation 1, we get:
Molar mass of mercury sulfide = 232.66 g/mol
Moles of mercury sulfide = 0.154 moles
Putting values in equation 1, we get:
[tex]0.154mol=\frac{\text{Mass of mercury sulfide}}{232.66g/mol}\\\\\text{Mass of mercury sulfide}=35.82g[/tex]
Hence, the excess reagent for the given chemical reaction is mercury (II) perchlorate and the amount left after the completion of reaction is 0.048 moles. The amount of mercury sulfide formed in the reaction is 35.82 grams.
We need to find the limiting reactant based on the moles of each reactant in the solution, based on which we can calculate the mass of the solid precipitate that will form and the mass of the reactant in excess that will remain.
Explanation:To solve this problem, we bring in the concept of limiting reactants in a chemical reaction. The limiting reactant is the reactant that is completely consumed in a reaction and determines the maximum amount of product that can be formed. The reaction between mercury(II) perchlorate (Hg(ClO4)2) and sodium sulfide (Na2S) results in the formation of a precipitate. Based on the provided masses, we first need to calculate the moles of each reactant. We'd then compare the stoichiometric ratios to determine the limiting reactant.
After determining the limiting reactant, we can use stoichiometry to calculate how much of the precipitate will form. Furthermore, we can calculate the remaining quantity of the reactant in excess after the reaction.
Please note that the exact calculations require the molecular weights of the reactants and knowledge about the balanced chemical equation of the reaction.
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