Volt is the unit to measure cell potential.
Explanation:
The cell potential is the measure of potential difference in the two halves of the electrochemical cell.
It is the measure of how much voltage exists between the two halves of the battery. The unit of volt is joule/coulomb. The cell potential is measured by voltmeter.
The energy per unit charge from the oxidation-reduction reaction to drive the reaction is cell potential.
What is the percent yield if 4.65 grams of copper is produced when 1.897 grams of aluminum reacts with an excess of copper (II) sulfate?
2Al + 3CuSO4 (aq) —> Al2(SO4)3 (aq) + 3Cu
The percentage yield if 4.65 g of copper is produced will be 70.4 %.
Explanation:
The balanced equation is given as
2Al + 3CuSO4 ----> Al2(SO4)3 + 3Cu
1.87 g of Al = 0.0693 moles of Al * 3 moles of Cu / 2 moles of Al
= 0.10396 moles of Cu.
This corresponds to 6.606 g of Cu which refers to theoretical yield.
% yield = (actual / theoretical) * 100
= (4.65 / 6.606) * 100
% yield = 70.4 %.
To calculate the percent yield for copper production, convert the given mass of aluminum to moles, use stoichiometry to determine the theoretical yield of copper, and then divide the actual yield by the theoretical yield and multiply by 100%.
Explanation:To calculate the percent yield in the reaction where 1.897 grams of aluminum reacts with an excess of copper (II) sulfate to produce copper, we first need to determine the theoretical yield of copper that can be produced from the given amount of aluminum. Utilizing stoichiometry, we start with the balanced chemical equation:
2Al + 3CuSO4 (aq) → Al2(SO4)3 (aq) + 3Cu
This equation tells us that 2 moles of aluminum can produce 3 moles of copper. However, since we have the mass of aluminum, we need to convert it to moles using aluminum's molar mass. Then by the stoichiometric relationship, we can find out how many moles of copper would theoretically be formed and then convert that number to grams by using the molar mass of copper.
Once the theoretical yield is found, we use the actual yield (4.65 grams) to calculate the percent yield using the following formula:
percent yield = (actual yield / theoretical yield) x 100%
Note that in some cases, the theoretical yield may need to be determined by other means, such as by identifying the limiting reactant if not all reactants are in excess. For the provided example, the theoretical yield can be calculated directly since the aluminum is limiting and is completely consumed in the reaction.
Along which type of front is the intensity of precipitation greater, but the duration
shorter?
A.) cold
B.)warm
C.)stationary
D.)backwards
Answer:
Cold Front
Explanation:
Determine the empirical formula of an organic hydrocarbon compound that contains 80% by mass of carbon and 20% by mass of hydrogen. If the Mr of the compound is 30, what is the molecular formula?
Answer: ethane
Explanation:
To determine the empirical formula of a hydrocarbon with 80% carbon and 20% hydrogen, calculate the moles of each and establish the simplest whole number ratio, which is CH₃. The molecular formula is then derived by dividing the molar mass of the compound by the empirical formula mass; since Mr is 30, the molecular formula is C₂H₆.
Determining Empirical and Molecular Formulas
To determine the empirical formula of an organic hydrocarbon compound with 80% carbon and 20% hydrogen by mass, assume a 100 g sample of the compound. This assumption simplifies the calculation because the percentages can be directly treated as grams:
80 g carbon (C)
20 g hydrogen (H)
Next, convert these masses into moles based on the atomic masses of carbon and hydrogen (approximately 12.01 g/mol for C and 1.01 g/mol for H):
Carbon: 80 g C ÷ 12.01 g/mol C = approximately 6.66 mol C
Hydrogen: 20 g H ÷ 1.01 g/mol H = approximately 19.80 mol H
Divide the moles of each element by the smallest number of moles to get a ratio:
Ratio of C:H = 6.66 mol C : 19.80 mol H = 1:3
So, the empirical formula is CH₃.
Next, to find the molecular formula, we need to use the given molar mass (Mr) of the compound, which is 30 g/mol. Since the empirical formula mass of CH₃ is about 15.03 g/mol (12.01 for C + 3 × 1.01 for H), we divide the molar mass of the compound by the empirical formula mass:
30 g/mol ÷ 15.03 g/mol
This gives us a ratio of approximately 2, suggesting that the molecular formula is twice that of the empirical formula. Therefore, the molecular formula is C₂H₆.
How can you lower the pH of the vinegar?
A. Mix the vinegar with sugar to thicken it
B. Boil the vinegar to concentrate it.
C. Freeze the vinegar to change its state.
D. Add water to the vinegar to dilute it.
To lower the pH of vinegar, it should be boiled to concentrate the acetic acid. Mixing vinegar with baking soda triggers a reaction where bicarbonate acts as a base.
Explanation:To lower the pH of vinegar, which means to make it more acidic, one should concentrate the acetic acid content in the vinegar. This can be done by option B, boiling the vinegar to concentrate it. Boiling causes the water to evaporate, leaving behind a higher concentration of acetic acid. Adding sugar, freezing, or diluting with water would not lower the pH, but diluting with water would actually raise the pH, making the vinegar less acidic.
When vinegar and baking soda are mixed, a chemical reaction occurs, producing carbon dioxide gas, water, and sodium acetate. However, the question requires an understanding of what species in vinegar serves as a base. In the reaction with baking soda (sodium bicarbonate), vinegar (acetic acid) acts as the acid, and the bicarbonate ion in baking soda acts as the base.
Final answer:
To lower the pH of vinegar, you can add water to dilute it, which decreases the concentration of acetic acid.
Explanation:
To lower the pH of vinegar, you can add water to dilute it. When you add water to vinegar, it increases the amount of solvent and decreases the concentration of acetic acid, which is responsible for the acidic properties of vinegar. This dilution results in a lower pH.
What is the wavelength of a wave having a frequency of 3.76x10^14
Answer:
3.76 x 1014 s-1? λ = c/ν = 3.00 x 108 m/s = 7.98 x 10-7 m 3.76 x 1014 s-1.
Explanation:
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The value of wavelength with a frequency value of [tex] 3.76 \times {10}^{14} [/tex] is [tex] 7.97 \times {10}^{ - 5} \: Hz[/tex]
Recall :
f = c / λWhere, f = frequency ; c = speed of light = [tex]3 \times {10}^{8} [/tex] λ = wavelength = [tex]3.76 \times {10}^{14} Hz[/tex]Substituting the values into the equation :
[tex]wavelength = \frac{3 \times {10}^{8} }{3.76 \times {10}^{14} } = 0.7979 \times {10}^{(8 - 14)} = 0.7979 \times {10}^{ - 6} [/tex]
Therefore the value of wavelength , λ for the given frequency value is : [tex]7.98 \times {10}^{ - 5} Hz[/tex]
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give the name of the following organic compound CH3 _O _CH3
Answer:
Dimethyl ether
Explanation:
There r 2 in this. In the straight chain carbon there are 2 of there so we name it as di. It is methyl so we gave it methyl.
Answer:
Dimethyl ether (methoxymethane)
Explanation:
what is the density of a liquid if 95.5cm cubed has a mass of 101 grams?
Answer:
1.06 g/cm³
Explanation:
Data given:
volume of liquid = 95.5 cm³
mass of the liquid = 101 g
density = ?
Solution:
To calculate density formula will be used
d = m/v
where
d = density
m = mass
v = volume
put values in above formula
d = 101 g / 95.5 cm³
d = 1.06 g/cm³
so. the density of liquid = 1.06 g/cm³
Final answer:
The density of a liquid, given its mass is 101 grams and volume is 95.5 cm³, is calculated using the formula Density = Mass / Volume, resulting in a density of 1.057 g/cm³.
Explanation:
The question asks to calculate the density of a liquid when given its mass and volume. Density is found by dividing the mass of a substance by its volume. We can use the formula Density = Mass / Volume to find the answer.
In this case, the mass of the liquid is 101 grams and the volume is 95.5 cm3. Plugging these values into the formula gives:
Density = 101 grams / 95.5 cm3 = 1.057 g/cm3.
Therefore, the density of the liquid is 1.057 g/cm3.
2 FeCl2 + Cl2 → 2 FeCl3
If 1.1898 moles of FeCl2 are reacted, how many moles of Cl2 will also be reacted?
Answer:
0.5949 mol Cl2
Explanation:
1. Balance equation - that was given
2. Identify the "given" and what is being asked
-Given moles of FeCl2, Find moles of Cl2
List other known quantites - 1 mol Cl2 = 2 mol FeCl2 (given based on the equation)
3. Prepare a concept map = mol FeCl2 -> mol O2
(Equation should be set up like: 1mol Cl2/2 mol FeCl2)
4. Cancel units and calculate:
----> 1.1898 mol FeCl2 x 1 mol Cl2/2 mol FeCl2 = 0.5949 mol Cl2 will be reacted
How many electrons can fit in each subshell?
Answer: each subshell can hold 2 electrons.
What is the answer please
What is the length in inches of a 100-meter field?
Answer: 3937 inches
Explanation: The conversion factor of 1m = 39.37 inches
Solution:
100 m x 39.37 in / 1 m
= 3937 inches
Cancel out meters so the remaining unit is in inches
A reaction mixture that consisted of 0.35 molH2and 1.6 mol I2 was introduced into a 2 L flask and heated. At the equilibrium, 60% of the hydrogen gas had reacted. What is the equilibrium constant Kc for the reactionH2(g) + I2(g)⇀↽2 HI(g)at this temperature?
Answer:
The equilibrium constant Kc for the reaction is :
16.07
Explanation:
The balanced equation is :
[tex]H_{2}(g)+I_{2}(g)\rightleftharpoons 2HI(g)[/tex]
First ,
"At the equilibrium, 60% of the hydrogen gas had reacted"
This means the degree of dissociation = 60% = 0.6
Here we are denoting degree of dissociation by ="x" = 0.6
Now , consider the equation again,
[tex]H_{2}(g)+I_{2}(g)\rightleftharpoons 2HI(g)[/tex]
H2 I2 2HI
0.35 1.6 0 (Initial Concentration)
0.35(1 - x) 1.6(1 - x) 2x (At equilibrium)
0.35(1 - 0.6) 1.6(1 - 0.6) 2(0.6)
0.14 0.64 1.2
calculate the concentration of each:
[tex]Concentration =\frac{moles}{Volume(L)}[/tex]
[tex]C_{H_{2}}=\frac{0.14}{2}[/tex]
[tex]C_{H_{2}}=0.07moles/L[/tex]
[tex]C_{I_{2}}=\frac{0.64}{2}[/tex]
[tex]C_{I_{2}}=0.32moles/L[/tex]
[tex]HI=\frac{1.2}{2}[/tex]
[tex]HI=0.6moles/L[/tex]
The equilibrium constant for this reaction "Kc" can be written as:
[tex]Kc=\frac{[HI]^{2}}{[H_{2}][I_{2}]}[/tex]
[tex]Kc=\frac{0.6^{2}}{0.07\times 0.32}[/tex]
[tex]Kc=\frac{0.36}{0.0224}[/tex]
[tex]Kc=16.07[/tex]
Which number represents runoff on the hydrologic cycle diagram?
1
2
3
4
Illustration of water cycle showing land and water body with arrows pointing outward and inward to both land and water body and some numeric labels one, two, three, and four mentioned along with arrows
Answer:
4
Explanation:
I took the test and got it right!
which law represents a balanced chemical equation?
Answer:
All chemical equations goes to the law of conservation of mass which says that matter can not be destroyed nor created which means there has to be an equal amount of atoms of each element on both sides of the equation. I hope that helps, I'm learning this as well.
Answer:
The law of conservation of mass, this is what I got correct on a test hopefully this helps Im sorry I don’t have any written proof. Please tell me if this is incorrect:)
Explanation:
Is carbon or chlorine more reactive? Why?
Answer: I’ve got you man ,
Cl has comparitively huger size than carbon and needs just one electron to fill its valence shell and be stable. ... Hydrogen is a halogen and is above chlorine in the 17th group but still it is not more electronegative than chlorine.
Explanation:
have a good day
Final answer:
Chlorine is more reactive than carbon because the bonds between chlorine atoms are weaker compared to the strong carbon-fluorine bonds. Reactivity increases from fluorides to iodides, with chlorides being more reactive than fluorides due to easier bond breaking.
Explanation:
In terms of reactivity, the key factor is the strength of the bonds that need to be broken for a reaction to occur. A carbon-chlorine bond is relatively strong but not as strong as a carbon-fluorine bond. Therefore, in a series of carbon-halogen bonds, the strength decreases and thus reactivity increases in the following order: C-F (least reactive), C-Cl, C-Br, to C-I (most reactive).
Looking specifically at chlorine, it forms diatomic molecules (Cl₂) with a relatively weak bond between the atoms, making Cl₂ quite reactive. Chlorine reacts with a variety of substances, including metals, to form chlorides. Considering alkyl halides, iodides are the most reactive and fluorides the least because it is easiest to break a carbon-iodine bond and hardest to break a carbon-fluorine bond.
The reactivity of chlorination products must take into account the polarity of the bond. The carbon-chlorine bond's polarization leads to increased reactivity as it can be more easily attacked due to its partial positive charge on the carbon atom.
which of thur following careers requires chemistry knowledge?
a. doctor
b. pharmacist
c. forensics expert
d. all of the above
Answer:
All of them.
Explanation:
They all require some sort of chemistry knowledge as they might be dealing with substances.
Doctors, pharmacists, and forensics experts all require chemistry knowledge in their respective fields to understand interactions and chemical compositions pertaining to medicines, drugs, and evidence.
Explanation:The correct answer to the question 'Which of the following careers requires chemistry knowledge?' is d. all of the above. Each of these professions requires some knowledge of chemistry:
Doctors need to understand how different medicines interact with the body's chemistry. As for pharmacists, their whole job revolves around the chemical compositions of drugs and how they can benefit or harm patients. Lastly, forensics experts often use chemistry to analyze evidence collected from crime scenes. Learn more about Chemistry in Careers here:
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V 2 O 5 + Cl 2 VOCl 3 + O 2
How many moles of V 2 O 5 are required to produce 7.0 moles of VOCl 3 ?
Answer: 3.5 moles V2O5
Explanation: First balance the chemical equation to find the stoichiometric factor between VOCl3 and V2O5
2 V2O5 + 6 Cl2 => 4 VOCl3 + 7 O2
So the mole to mole ratio is 2 moles V2O5 to 4 moles of VOCl3
Solution
7 moles VOCl3 x 2 moles V2O5 / 4 moles VOCl3 = 3.5 moles V2O5
Visible light, which has a wavelength of between 380 nm and 760 nm, is usually
A.
changed to a different wavelength by the atmosphere.
B.
not fully absorbed by the atmosphere.
C.
completely destroyed by the atmosphere.
D.
fully absorbed by the atmosphere.
Answer:
not fully absorbed by the atmosphere.
Explanation:
Visible light with a wavelength of 380-760 nm will usually not be fully absorbed by the atmosphere. Visible light is most likely to reach Earth's surface or be partially absorbed and scattered by the atmosphere. Other types of radiation, such as infrared radiation and ultraviolet light, are more readily absorbed by the atmosphere.
Answer:
not fully absorbed by the atmosphere.
Explanation:
Visible light with a wavelength of 380-760 nm will usually not be fully absorbed by the atmosphere. Visible light is most likely to reach Earth's surface or be partially absorbed and scattered by the atmosphere. Other types of radiation, such as infrared radiation and ultraviolet light, are more readily absorbed by the atmosphere.
In your own words, explain how/why precipitates form. Also explain what spectator ions are.
A precipitate is a product of a reaction that is insoluble in the reaction medium (usually water).
Why?
One of the signs that a reaction happened is that a precipitate forms. Let's take the reaction between Silver Nitrate (AgNO₃) and Sodium Chloride (NaCl) as an example:
AgNO₃(aq) + NaCl(aq) → AgCl(s)↓ + NaNO₃(aq)
In this reaction, Silver Chloride (AgCl) is an insoluble product of the reaction, and precipitates out of the reaction medium
If we write down the ionic equation, we find out the following:
Ag⁺ + NO₃⁻ + Na⁺ + Cl⁻ → AgCl(s) + Na⁺ + NO₃⁻
The ions that appear at both sides of the arrow are called spectator ions, since they are not directly involved in the process of the reaction, making the net ionic equation to be:
Ag⁺ + NO₃⁻ → AgCl(s)
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HBr + Mg(OH)2 MgBr2 + H2O
Answer:
2HBr + Mg(OH)2 => MgBr2 + 2 H2O
Explanation: To balance the equation put 2 in H2O in the product side. Then balance the other Hydrogen atoms by adding 2 in HBr. Since there is another 2 atoms of H in (OH)2 so hydrogen atoms are balanced having 4 atoms each sides. Also Mg and Br are balanced
A gas occupies a volume of 410 mL at 27°C and 740 mm Hg pressure. Calculate the volume the gas
would occupy at 250.°C and 680 mm Hg pressure.
The problem requires using the combined gas law, which involves an equation relating pressures, volumes, and temperatures of a gas sample. By converting temperatures to Kelvin and using given pressure and volume values, we can solve for the final volume.
Explanation:The question involves using the combined gas law to calculate the new volume of a gas given changes in temperature and pressure. To find the volume the gas would occupy at 250°C and 680 mm Hg pressure, we use the formula:
V2 = (P1 × V1 × T2) / (P2 × T1)
First, we need to convert the temperatures from Celsius to Kelvin:
Initial temperature: T1 = 27°C + 273.15 = 300.15 KFinal temperature: T2 = 250°C + 273.15 = 523.15 KNow we plug the values into the combined gas law equation:
V2 = (740 mm Hg × 410 mL × 523.15 K) / (680 mm Hg × 300.15 K)
After doing the math, you can find the final volume, V2, in milliliters (mL).
If I contain 3 moles of gas in a container with a volume of 60 liters and at a
temperature of 400 K, what is the pressure inside the container? (Use mm Hg)
Answer: n = 3.0 moles
V = 60.0 L
T = 400 K
From PV = nRT, you can find P
P = nRT/V = (3.0 mol)(0.0821 L-atm/K-mol)(400 K)/60.0L
P = 1.642 atm = 1.6 atm (to 2 significant figures)
Final answer:
The pressure inside a container with 3 moles of gas, a volume of 60 liters, and a temperature of 400 K is approximately 1247.2 mm Hg, calculated using the Ideal Gas Law.
Explanation:
To calculate the pressure inside the container we can use the Ideal Gas Law, which is expressed as PV = nRT. In this formula, P stands for pressure, V for volume, n for number of moles, R for the ideal gas constant, and T for temperature. The ideal gas constant (R) has various values depending on the units of pressure and volume.
For this problem, we will use R = 62.36 L mm Hg / mol K, since we are asked to find the pressure in millimeters of mercury (mm Hg) and the volume is given in liters (L).
First, we need to correctly plug in our given values: we have n = 3 moles, V = 60 liters, and T = 400 K. When these values are substituted into the ideal gas equation, we get P(60 L) = (3 moles)(62.36 L mm Hg / mol K)(400 K).
Solving for pressure P gives us:
P = (3 moles × 62.36 L mm Hg / mol K × 400 K) / 60 L
Now, let's do the math:
P = (74832 mm Hg K / mol) / 60 L= 1247.2 mm Hg
The pressure inside the container is therefore approximately 1247.2 mm Hg.
Which solution has the greater concentration?
A. 0.500 mole LiCl dissolved in 250 ml solution
B. 0.250 mole LiCl dissolved in 250 ml of solution
C. Both the same
The higher concentrated solution is 0.250 mole LiCl dissolved in 250 ml of solution
( B).0.250mole of LiCl diluted in 250ml solution
Explanation:
Procedure to find the intensity of the solution:
To find the intensity of the solution, we have to use the following formula
M1V1=M2V2
250mL of a 0.500 M aqueous solution of LiCl is diluted with water
[tex]M1V1=(250) \times (0.500)=125M[/tex]
250 ml of a 0.250M aqueous solution of LiCl is diluted with water
[tex]M2V2=(250) \times (0.250)=62.5M[/tex]
Thus the PH level of a solution increases from ascending order, Therefore the Solution with 62.5M is a higher concentration than that of the solution with 125M.
When iron reacts with oxygen in the air , it forms iron (III) oxide or rust .
How many grams of iron (III) Oxide would be formed if 2 moles of iron completely react with oxygen gas ?
A. 319.2 g
B. 159.6 g
C. 71.8 g
D. 143.6 g
Answer:
B. 159.6 g
Explanation:
balanced reaction:
4Fe + 3O2 → 2Fe2O3∴ moles taht react of Fe = 2 mol
∴ mm Fe = 55.845 g/mol
⇒ g Fe2O3 = ?
∴ moles Fe2O3 = ( 2 mol Fe )×( 2 mol Fe2O3/ 4 mol Fe ) = mol Fe2O3
∴ mm Fe2O3 = 159.6882 g/mol
⇒ g Fe2O3 = ( 1 mol Fe2O3 )×( 159.6882 g/mol) = 159.6882 g
The speed of a chemical reaction
a. is constant no matter what the temperature is.
b. is independent of the amount of contact surface of a solid involved.
c. between gases should in all cases be extremely rapid because the average kinetic energy of the
molecules is great.
d. between ions in aqueous solution is extremely rapid because there are no bonds that need to be
broken.
1
Answer: option C. between gases should in all cases be extremely rapid because the average kinetic energy of the molecules is great.
The speed of a chemical reaction is influenced by temperature and concentration. Reactions between gases are generally rapid due to the high average kinetic energy of the molecules.
Explanation:The speed of a chemical reaction is influenced by various factors, including temperature, concentration, and the nature of the reactants. The statement that best aligns with these factors is: c. Between gases should in all cases be extremely rapid because the average kinetic energy of the molecules is great.
Temperature plays a crucial role in determining the speed of a reaction. Increasing the temperature increases the kinetic energy of the molecules, causing them to move faster and collide more frequently, leading to faster reaction rates. Additionally, the statement that mentions the effect of concentration on reaction rates is: When a reaction occurs between two reactant species, it proceeds faster at higher concentrations of the reactants.
It is important to note that factors like surface area and the presence of bonds to be broken also influence reaction rates, but they are not addressed in the given options.
Which of the following increases the Ht concentration in solution?
O
A. A base
O
B. Water
O
C. Salt
O
D. An acid
Answer:
The H⁺ concentration in solution is increased by an Acid.
Explanation:
To understand this we will simply define each given option.
An Acid:
Is any specie which when dissolved in water increases the concentration of Hydrogen Ions (i.e. H⁺) like HCl, or donated H⁺ to base like HBr or accepts lone pair electrons like BF₃.
Salt:
Salt is formed from the neutralization reaction of Acid and Base. So, when the salt is formed it decreases both the concentration of H⁺ or Hydroxide ions if present.
Base:
It is any specie which when dissolved in solution produces hydroxyl ions like NaOH, or accepts proton or donate lone pair of electrons like :NH₃.
Water:
Water is neither an acid nor a base. It is a neutral compound which on ionization produces hydroxyl and hydrogen ions at the same time which at that time neutralize each other. Hence, we can conclude that water does not increase the concentration of H⁺ ions.
Gravity is dependent on which of the two factors?
mass and weight
distance and weight
mass and force
mass and distance
Answer:
mass and weight
Explanation:
because ur weight pulls you to the center of the earth
9. lonization energy is the amount of energy necessary to
Answer: Remove a loosely bound valence electron from a gaseous atom on its orbital shell.
Explanation: It is the minimum energy required to pull out outer electrons on its energy orbital.
Which of the following reactions is endothermic?
H2(g) + ½O2(g) → H2O(g), ΔH = -57.82 kcal
½N2(g) + O2(g) + 8.1 kcal → NO2(g)
½N2(g) + 3/2H2(g) → NH3(g) + 11.0 kcal
C(diamond) + O2(g) → CO2, ΔH = -94.50 kcal
Explanation:
Chemical reaction
When two or more substances react and form some new substance it is called as chemical reaction .
A + B --> C + D
(reactants ) (products )
When ever chemical reaction occurs following changes can occur :
Change in colour Ppt formation energy changes Change in stateEvolution of gas etcOn the basis of energy changes : reactions are of two types :
Endothermic
Exothermic
Endothermic reaction
A reaction in which heat is absorbed .
Example :½N2(g) + O2(g) + 8.1 kcal → NO2(g)
Exothermic reaction
A reaction in which heat is released .
For example : H2(g) + ½O2(g) → H2O(g), ΔH = -57.82 kcal
½N2(g) + 3/2H2(g) → NH3(g) + 11.0 kcal
C(diamond) + O2(g) → CO2, ΔH = -94.50 kcal
Final answer:
The reactions ½N2(g) + O2(g) + 8.1 kcal → NO2(g) and ½N2(g) + 3/2H2(g) → NH3(g) + 11.0 kcal are endothermic because they absorb heat, as indicated by their positive ΔH values.
Explanation:
To determine whether a chemical reaction is exothermic or endothermic, we need to look at the heat term (ΔH) associated with the reaction. An exothermic reaction releases heat and therefore has a negative ΔH value. An endothermic reaction absorbs heat and has a positive ΔH value.
In the examples provided:
H2(g) + ½O2(g) → H2O(g), ΔH = -57.82 kcal is exothermic because heat is released (negative ΔH).½N2(g) + O2(g) + 8.1 kcal → NO2(g) is endothermic because heat is absorbed (positive ΔH).½N2(g) + 3/2H2(g) → NH3(g) + 11.0 kcal is endothermic because it absorbs heat (positive ΔH).C(diamond) + O2(g) → CO2, ΔH = -94.50 kcal is exothermic due to the release of heat (negative ΔH).Therefore, the reactions ½N2(g) + O2(g) + 8.1 kcal → NO2(g) and ½N2(g) + 3/2H2(g) → NH3(g) + 11.0 kcal are both endothermic reactions.
high viscosity at higher temperatures
unreactive with other substances
liquid at high temperatures
organic compound
poor conductor of electricity
Based on the provided chemical and physical properties of the unknown substance. It would be MOST useful as a(n)
A) machinery lubricant.
B) heat insulator in a home.
C) internal combustion engine fuel.
D) electrical conductor in a computer circuit.
Answer:
A
Explanation:
USA Test prep
The given chemical and physical properties can be most useful as a machinery lubricant. Therefore, option A is correct.
What are lubricants?A lubricant can be described as a substance that helps to decrease friction between surfaces in mutual contact, which reduces the heat produced when the surfaces move.
The lubricant-to-surface friction is generally much less than surface-to-surface friction without any lubrication. Therefore, the use of a lubricant reduces friction in types of machinery.
It has the function of transmitting forces, transporting particles, or heating or cooling the surfaces. The property of reducing friction between the surfaces is called lubricity.
A machine lubricant has the property to stay liquid within a wide range of temperatures. They have high viscosity index, thermal stability, Hydraulic stability, Corrosion prevention, and high resistance to oxidation.
These properties of Lubricants are the same as the given chemical and physical properties. Therefore, the given properties can be useful as a machinery lubricant.
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