Answer:
8.0 M.
Explanation:
It is known that the no. of millimoles after dilution is equal to the no. of millimoles before dilution.∴ (MV) of KNO₃ before dilution = (MV) of KNO₃ before dilution.
Before dilution:
M = 12.0 M, V = 500.0 mL.
After dilution:M = ??? M, V = 500.0 mL + 250.0 mL = 750.0 mL.
∴ M after dilution = (MV) before dilution / (V) after dilution = (12.0 M)(500.0 mL)/(750.0 mL) = 8.0 M.
Select the correct answer. In which state of matter do molecules have the lowest kinetic energy? A. liquid state B. plasma state C. gaseous state D. solid state
Answer:
D. Solid state
Explanation:
In solid state the particles of a substance, vibrate in fixed positions though they posses less kinetic energy. This is the reason as to why the particles do not move far apart from each other making the solids remain in fixed shapes unless an extra energy is added.
Since solids cannot move and can only fluctuate around their mean position, they have the lowest kinetic energy. Despite the fact that liquids have more kinetic energy than solids. Here the correct option is D.
Solids are composed of the least energy particles. They are packed close together, giving them little room to maneuver. The energy of a gas's particles is the highest, with a liquid's particles having higher energy than a solid's.
A pure substance has more energy in its gaseous state than it does in its liquid state, which has more energy than it does in its solid state. When particles are in a gaseous form, their kinetic energy is at its maximum.
Thus the correct option is D.
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A rocket is designed to drop its first stage mid-flight. Due to a malfunction, this does not occur. What is a possible result of this malfunction
Answer:
The rocket is now too heavy to reach its destination.
Matter are anything that is made up of atoms. The quantity of matter can be observed only on the basis of mass and volume calculation. Thus the rocket has become too hefty to get to its destination.
What is matter?Matter is a substance that has some mass and can occupy some volume. The matter is mainly used in science. Matter can be solid, liquid or gas.
Matter is anything that is made up of atoms. Anything around us that can be physically seen and touched are matter. Ice, water and water vapors are example of matter.
So as we saw that matter has some mass so mass can be measured in gram only. Mass can also be represented as number of molecules. We also saw that matter occupy some volume and that volume is measured only in liter. A rocket is designed to drop its first stage mid-flight. Due to a malfunction, this does not occur. The possible result of this malfunction is that the rocket has become too hefty to get to its destination.
Thus the rocket has become too hefty to get to its destination.
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The coefficients in a chemical equation represent the
Answer:
The coefficients in a chemical equation represent the relative number of moles of each reactant and product that interven in the chemical reaction.Explanation:
The coefficients are the numbers that you put in front of each chemical formula that represents the reactants and products in the chemical equation. They indicate the mole ratio in which the elements or compounds react to form the products, as per the chemical equation.
See an example:
Word equation: hydrogen and oxygen produce waterChemical (skeleton) equation: H₂ (g) + O₂(g) → H₂O (g)This equation is not balanced: the number of atoms of oxygenin the reactant side is 2 while the number of atoms of oxygen isn the product side is 1. In order to balance the equation you need to add some coefficients.
When no coefficients are shown it is understood that the coefficient is 1.
Balanced chemical equation: 2H₂ (g) + O₂(g) → 2H₂O (g)The coefficients 2 in front of H₂ and 1 (understood) in front of O₂, in the reactant side, and 2 in front of H₂O, in the product side, balance the equation.
Those coefficients mean that the 2 molecules (or mole of molecules) of H₂ react with 1 molecule (or mole of molecules) of O₂ to form 2 molecules (or moles) of H₂O (product side).
That is the mole ratio: 2 H₂ : 1 O₂ : 2 H₂O.
Notice that, in spite of the aboslute numbers may change, the mole ratio is unique for any chemical reaction. For example 4 : 2 : 4 is the same ratio that 2 : 1 : 2, or 8 : 4 : 8, but the most common practice is to use the most simple form of the ratio, i.e. 2: 1: 2.
The representation that coefficients that are found in a chemical equation provide, is : number of moles that is present in the reactants as well as products.
The coefficients of the equation helps to know the number of moles that is present in reactants as well as products in a balanced equation.If the equation is not balanced, then it needs to be balanced first, with information of the coefficients, it is possible to calculate components of reactants as well as the products that is taking part in the chemical reaction.Learn more at:
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A beaker containing 80 grams of lead(ii) nitrate, pb(no3)2, in 100 grams of water has a temperature of 30 ºc. approximately how many grams of the salt are undissolved, on the bottom of the beaker?
Answer:
14 g.
Explanation:
From the figure attached:the solubility of lead(II) nitrate, Pb(NO₃)₂, in 100 grams of water has a temperature of 30ºC is (66 g).
When beaker containing 80 grams of lead(II) nitrate, Pb(NO₃)₂, in 100 grams of water has a temperature of 30ºC.
∴ The grams of the salt are undissolved, on the bottom of the beaker are (14 g).
80 grams of lead(II) nitrate in 100 grams of water at 30ºC results in 66 grams (option c) of undissolved lead(II) nitrate.
To solve this problem, we need to know the solubility of lead(II) nitrate (Pb(NO₃)₂) in water at 30 ºC.
The solubility of Pb(NO₃)₂ in water at 30 ºC is approximately 122 g/100 mL.
Since we have 100 grams of water, we can calculate the maximum amount of Pb(NO₃)₂ that can dissolve:
Maximum soluble Pb(NO₃)₂ = 122 g/100 mL × 100 g / 1000 mL = 12.2 g
We started with 80 grams of Pb(NO₃)₂, so the amount of undissolved salt is:
Undissolved Pb(NO₃)₂ = 80 g - 12.2 g = 67.8 g ≈ 66g
Therefore, approximately 66 grams of lead(II) nitrate remain undissolved at the bottom of the beaker.
Complete Question - A beaker containing 80 grams of lead(II) nitrate, Pb(NO₃)₂, in 100 grams of water has a temperature of 30 ºC. Approximately how many grams of the salt are undissolved, on the bottom of the beaker?
a) 20 grams
b) 80 grams
c) 66 grams
d) 14 grams
What is the charge of an electron
A. -1
B. 0
C. +1
D. +2
Answer:
A
Explanation:
I believe it is negative 1.
Answer:
(A) -1
Explanation:
I just did it on edge :)
What law states that the physical and chemical properties of the elements are periodic within the sequence of their atomic numbers?
Atomic Law
Periodic Law
Octet Law
Valence Law
Answer:
Periodic Law.
Explanation:
The Periodic Law states that the physical and chemical properties of the elements repeat in a systematic and predictable way when the elements are arranged in order of increasing atomic number.
Many of the properties are repeated at intervals.
When the elements are arranged correctly, the trends in element properties become apparent and can be used to make predictions about unknown or unfamiliar elements, simply based on their placement on the table.
Answer:
Periodic Law
Explanation:
Carbon-14 emits beta radiation and decays with a half-life (t ) of 5730 years. Assume that you start with a mass of 6.00 × 10^–12 g of carbon 14. How many grams of the isotope remains at the end of three half-lives?
Answer:
did you ever find the answer
Explanation:
Answer: [tex]0.75\times 10^{-12}[/tex]
Explanation:
Formula used :
[tex]a=\frac{a_o}{2^n}[/tex]
where,
a = amount of reactant left after n-half lives = ?
[tex]a_o[/tex] = Initial amount of the reactant = [tex]6\times 10^{-12} g[/tex]
n = number of half lives = 3
Putting values in above equation, we get:
[tex]a=\frac{6\times 10^{-12} }{2^3}[/tex]
[tex]a=\frac{6\times 10^{-12} }{8}[/tex]
[tex]a=0.75\times 10^{-12}[/tex]
Therefore, the amount of carbon-14 left after 3 half lives will be [tex]0.75\times 10^{-12}g[/tex]
Blaise Pascal discovered that changes in pressure _____.
A. will decrease with depth of fluid
B. will increase with depth of fluid
C. will depend on the area
D. are transmitted equally through a fluid
Answer:
D. are transmitted equally through a fluid
Explanation:
Blaise Pascal discovered the Pascal's principle which states that the pressure applied to a fluid at a point inside a closed system will be transmitted equally in all directions through out the fluid.Pascal's principle has a wide range of application, for example in hydraulics such as car brakes which is the most used hydraulic system. The fluid used must be in compressible.Which of the following is a base–conjugate acid pair?
H2O and H3O+
H2O and H2PO4–
H2PO4– and HPO42–
H2PO4– and H3O+
Answer : The correct options is, [tex]H_2O\text{ and }H_3O^+[/tex]
Explanation :
According to the Bronsted Lowry conjugate acid-base pair concept, an acid is a substance which donates protons and a base is a substance which accepts protons.
From the given options, [tex]H_2O[/tex] and [tex]H_3O^+[/tex] represents a base-conjugate acid pair.
The balanced reaction will be :
[tex]H_2O+H^+\rightleftharpoons H_3O^+[/tex]
In this, [tex]H_2O[/tex] is a base which accepts a proton to form conjugate acid [tex]H_3O^+[/tex].
Hence, the correct options is, [tex]H_2O\text{ and }H_3O^+[/tex]
H₂PO₄⁻ and HPO₄²⁻ is a base–conjugate acid pair
In a chemical reaction, a base and its conjugate acid are related through the transfer of a proton (H⁺). In the given options, H₂PO₄⁻ (dihydrogen phosphate ion) can act as a base and HPO₄²⁻ (hydrogen phosphate ion) can act as its conjugate acid.
When H₂PO₄⁻ accepts a proton (H⁺), it forms HPO₄²⁻, gaining a positive charge. This is the process of protonation, where a base accepts a proton to become its conjugate acid.
H₂PO₄⁻ + H⁺ → HPO₄²⁻
Conversely, when HPO₄²⁻ donates a proton (H⁺), it forms H₂PO₄⁻, losing a positive charge. This is the process of deprotonation, where an acid donates a proton to become its conjugate base.
HPO₄²⁻ → H₂PO₄⁻ + H⁺
Therefore, H₂PO₄⁻ and HPO₄²⁻ form a base-conjugate acid pair. The other options do not represent a base-conjugate acid relationship. H₂O and H₃O⁺ are related as a base and its conjugate acid in the reverse reaction of H₃O⁺ donating a proton to form H₂O. H₂O and H₂PO₄⁻ are not related as a base-conjugate acid pair, as H₂O is a neutral molecule and H₂PO₄⁻ is a base. H₂PO₄⁻ and H₃O⁺ are not a base-conjugate acid pair as they both represent acids.
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chemical equations
a. describe chemical reactions
b. show how to write chemical formulas
c. give names for chemical compounds
d. describes only biological changes
chemical equations: describe chemical reactions
Answer: a
I think this is the answer
Chemical equations describe chemical reactions. The correct option is a.
What are chemical equation?Chemical equations are a representation of a reaction in its numerical and chemical formula form.
For example ; [tex]\rm CH_4 + 2O_2 = CO_2 + 2O_2[/tex]
Thus, the correct option is a. describe chemical reactions.
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Two students are playing tug of war. If Student A is pulling the rope with 6N of force and Student B is pulling the rope with 9N of force, what is the net force
Answer:
3
Explanation:
If nitrogen (N) has 2 naturally occurring isotopes, nitrogen-14 (78.3%) and nitrogen-16 (21.7%), what is its average r.a.m.?
Answer:
14.434 r.a.m.
Explanation:
The atomic mass of an element is a weighted average of its isotopes in which the sum of the abundance of each isotope is equal to 1 or 100%.∵ The atomic mass of N = ∑(atomic mass of each isotope)(its abundance)
∴ The atomic mass of N = (atomic mass of N-14)(abundance of N-14) + (atomic mass of N-16)(abundance of N-16)
atomic mass of N-14 = 14.0 r.a.m, abundance of N-14 = percent of N-14/100 = 78.3/100 = 0.783.
atomic mass of N-16 = 16.0 r.a.m, abundance of N-16 = percent of N-16/100 = 21.7/100 = 0.217.
∴ The atomic mass of N = (atomic mass of N-14)(abundance of N-14) + (atomic mass of N-16)(abundance of N-16) = (14.0 r.a.m)(0.783) + (16.0 r.a.m)(0.217) = 14.434 r.a.m.
Sedimentary rocks found high in the Himalayan Mountains have been found with fossils of clams and other marine life. What does this indicate about the origin of the Himalayan Mountains? A) There was once a large ocean at top of the mountains. B) Animals that now live on the mountains once lived under water. C) The Earth's crust that formed these mountains was once covered with an ocean. D) Continental drift resulted two tectonic moving closer to each other over time.
Answer:
c
Explanation:
usa test prep
If you obtained 2.50 moles of CuSO4 from the reaction of CuO and H2SO4, but the theoretical yield was 3.19 moles, what was the percent yield?
Answer:
78.4%Explanation:
Just as context, write the chemical equation and the mole ratios
1) Balanced chemical equation:
CuO (s) + H₂SO₄ (aq) → CuSO₄ (aq) + H₂O (l)2) Therotetical (stoichiometric) mole ratios:
1 mol CuO : 1 mol H₂SO₄ : 1 mol CuSO₄ : 1 mol H₂OYou can calculate the percent yield from the amount of CuSO₄ obtained and the theoretical yield
3) Percent yield
Definition:Percent yield = (actual yield / theoretical yield)×100
Theoretical yiedl (given): 3.19 moles CuSO₄Actual yield (given): 2.50 moles CuSO₄Calcualtion:
Substitute the values in the formula:
Percent yield = (2.50 moles CuSO₄ / 3.19 moles CuSO₄)×100 = 78.4%What volume of carbon dioxide (CO2) will be produced if 2.90 moles of it on (Fe) is produced?
Answer:
= 97.44 Liters at S.T.P
Explanation:
The reaction between Iron (iii) oxide and Carbon monoxide is given by the equation;
Fe2O3(s)+ 3CO(g) → 3CO2(g) + 2Fe(s)
From the reaction when the reactants react, 2 moles of Fe and 3 moles of CO2 are produced.
Therefore; Mole ratio of Iron : Carbon dioxide is 2:3
Thus; Moles of Carbon dioxide = (2.9/2)×3
= 4.35 moles
But; 1 mole of CO2 at s.t.p occupies 22.4 liters
Therefore;
Mass of CO2 = 22.4 × 4.35 Moles
= 97.44 L
The volume of carbon dioxide produced is 97.44 L.
The equation of the reaction is;
Fe2O3 + 3CO --> 2Fe + 3CO2, we can see that the ratio of iron to carbon dioxide produced is 2:3.
From the reaction equation
3 moles of carbon dioxide is produced when 2 moles of iron is produced
x moles of carbon dioxide is produced when 2.9 moles of iron is produced
x = 3 moles × 2.9 moles/2 moles
x = 4.35 moles
If 1 moles of carbon dioxide occupies 22.4 L
4.35 moles of carbon dioxide occupies 4.35 moles × 22.4 L/ 1 moles = 97.44 L
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Which reaction model represents a nuclear fission reaction?
A → B + C
n + A → B + C + n
A + C → B + n
A → B + C + n
Answer: option B
Explanation: since nuclear fission involves the decay of larger nuclide into smaller nuclei along with Neutron when it is collide with Neutron.
Example Decay of U-235 into Kr and Ba along with 3 neutrons
Answer:
By presuming n denotes neutron, A is an atom and B & C are lighter nuclei, a reaction model of nuclear fission can be represented as follows:
n + A → B + C + n
Explanation:
A nuclear fission reaction is a process where a neuron collide with an atom and split it into two lighter nuclei and at the same time, a neuron and a large amount of energy will be released. The released neuron will then induce another nuclear fission on the next atom and repeat the same reaction process.
The understanding of nuclear fission play an important role in developing nuclear energy technology.
Which year was DNA evidence introduced?
1908
1988
1980
1998
1988 was when it was first introduced
Final answer:
DNA evidence was first introduced in 1988 and has since revolutionized forensic science. Its discovery by Miescher in 1869 and subsequent research paved the way for its pivotal role in modern biology and criminal justice.
Explanation:
DNA evidence was first introduced in 1988. This introduction of DNA for forensic purposes marked a monumental advancement in the field of criminal investigations and legal proceedings. The science of DNA was discovered by Friedrich Miescher in 1869, and significant developments unfolded over the years, leading to our contemporary understanding of DNA as the genetic material responsible for heredity. Experiments by scientists such as Oswald Avery, Colin MacLeod, and Maclyn McCarty in the 1940s, and the discovery of the 3D-double-helix structure by James Watson and Francis Crick in 1953, set the stage for the many applications of DNA science we see today, including forensic analysis.
The ksp of pbbr2 is 6.60×10−6 . What is the molar solubility of pbbr2 in pure water?
Answer:
The molar solubility is 0.0118 mole / liter = 1.18 × 10⁻² MExplanation:
1) Ksp stands for product solubility constant.
2) The product solubility constant is the equilibrium constant used for the aqueous ionization (dissolution) of low soluble ionic compounds.
3) The ionization or equilibrium reaction for the PbBr₂ is:
PbBr₂ (s) ⇄ Pb²⁺ (aq) + 2 Br(aq)⁻4) Sotichiometry:
PbBr₂ (s) ⇄ Pb²⁺ (aq) + 2 Br(aq)⁻Ao - x moles x 2x
5) Calculations:
Per definition of Ksp:
Ksp = [Pb²⁺] [Br(aq)⁻]² = (x) (2x)² = 4x³ Then, you have to solve: 6.60×10⁻⁶ = 4x³x³ = 6.60×10⁻⁶ / 4x = 0.0118 mole / liter = 1.18 × 10⁻² MThe molar solubility of PbBr₂ in pure water is solved from the solubility product constant (Ksp) and the dissolution stoichiometry. It involves setting up and solving the equation Ksp = 4s³ for the molar solubility 's'. The solution yields the molar solubility as approximately 1.12 x 10⁻² M.
Explanation:The molar solubility of PbBr₂ in pure water can be determined from its solubility product constant (Ksp). According to dissolution stoichiometry, the molar concentrations of Pb²⁺ and Br⁻ ions are equal and can be represented by 's' for molar solubility. The Ksp of PbBr₂ is therefore s * (2s)² (considering that there are two Br- ions for every PbBr₂ molecule that dissolves).
So Ksp = 4s³. Given Ksp is 6.60×10⁻⁶, we can solve the equation 4s³ = 6.60×10⁻⁶ for 's', the molar solubility.
The molar solubility 's' is a cube root of (6.60 × 10⁻⁶/4), which calculates approximately 1.12 x 10⁻² M.
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You should plan daily activities for extended staying guests.
True
False
This is true. You don’t want them to be bored
Answer:
The given statement on extended guest is false. The extended pay guest demand comfort and proper diet, not a schedule of daily activities.
Explanation:
The term extended stay guest refers to those people who live in hotels and other private lodges as guest for more span of time. The purpose of stay may include tour, medical issues, etc. These people demand comfort as well as first class food.
The main function of people who are offering such type of service must provide them with places and room which are more spacious and provides comfort as well as chefs who have good cooking talent. There is no need for planning daily activities as it is the hands of the guest to do it.
The absolute temperature of a gas is increased four times while maintaining a constant volume. What happens to the pressure of the gas?
Answer:
The pressure of a gas increases four times, when the absolute temperature is increased four times, while maintaining the volume constant.Explanation:
The expression that rules the change of temperature of ideal gases at constant volume is the Law of Gay-Lussac: pressure and temperature of gases are directly related. In the form of equations that is:
P / T = constantP₁ / T₁ = P₂ / T₂ .......... [equation 1]The question states that the absolute temperature is increased four times, the you can write that as T₂ = 4 × T₁, and substitute in the equation 1 to obtain:
P₁ / T₁ = P₂ / (4 × T₁)Simplify:
P₂ = P₁ × 4 × T₁ / T₁ = P₁ × 4That proves that the pressure also increases four times, when the absolute temperature is increased four times, while maintaining the volume constant.
Answer: The pressure will also increase 4 times.
Explanation:
To calculate the final temperature of the system, we use the equation given by Gay-Lussac Law. This law states that pressure of the gas is directly proportional to the temperature of the gas at constant pressure.
Mathematically,
[tex]\frac{P_1}{T_1}=\frac{P_2}{T_2}[/tex]
where,
[tex]P_1\text{ and }T_1[/tex] are the initial pressure and temperature of the gas.
[tex]P_2\text{ and }T_2[/tex] are the final pressure and temperature of the gas.
We are given:
[tex]P_1=p\\T_1=t\\P_2=?=\\T_2=4t[/tex]
Putting values in above equation, we get:
[tex]\frac{p}{t}=\frac{P_2}{4t}\\\\P_2=4p[/tex]
Hence, the pressure will also increase 4 times.
When a metal is heated in a flame, the flame has a distinctive color. This information was eventually extended to the study of stars because a red shift in star color indicates stars are moving away. star color indicates the distance from the earth. the line spectra of stars indicate which elements are present. it allows the observer to determine the size of stars.
Answer:
[tex]\boxed{\text{The line spectra of stars indicate which elements are present.}}[/tex]
Explanation:
Each element has a characteristic spectrum, so analyzing the line spectra of stars tell you what elements are present.
A is wrong. The statement is true, but its not the reason why astronomers study stars.
B is wrong. The colour is a function of the star's temperature.
D is wrong. Line spectra give no information on the size of stars.
The study of metals in chemistry is called inorganic metals.
The correct option is C.
Each metal when burns give the color due to the replacement of the electron because the amount of energy is increased due to heat.
According to the question, the rest of the option is wrong because they don't have any link with the hint.
Hence, the correct option is C that is the line spectra of stars indicating which elements are present.
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Determine the enthalpy:
4NH3(g) + 7O2(g) −→ 4NO2(g) + 6H2O(ℓ)
∆H◦ f species ( kJ mol)
NH3(g) −46.11
NO2(g) +33.2
H2O(ℓ) −285.83
1. −1899 kJ/mol rxn
2. +2034.4 kJ/mol rxn
3. −298.7 kJ/mol rxn
4. −1766 kJ/mol rxn
5. −1397.6 kJ/mol rxn
Answer:
Choice 5.: -1397.6 kJ/mol rxn.
Explanation:
Here's how to find the enthalpy change of a reaction [tex]\Delta H_\text{rxn}[/tex] from the standard enthalpy of formation [tex]\Delta H_\text{f}\textdegree{}[/tex] of each species.
Find the sum of [tex]\Delta H_\text{f}\textdegree{}[/tex] for the products: [tex]\Sigma \left[\Delta H_f\textdegree{}(\text{Products})]\right[/tex]. Multiply the [tex]\Delta H_\text{f}\textdegree{}[/tex] of each product by its coefficient in the equation. Find the sum of those products.Find the sum of enthalpies of formation [tex]\Delta H_\text{f}\textdegree{}[/tex] for the reactants: [tex]\Sigma \left[\Delta H_f\textdegree{}(\text{Reactants})]\right[/tex]. Similarly, multiply the [tex]\Delta H_\text{f}\textdegree{}[/tex] of each reactant by its coefficient in the equation. Find the sum of those products.The enthalpy change of this reaction is the same as the difference between [tex]\Sigma \left[\Delta H_f\textdegree{}(\text{Products})]\right[/tex] and [tex]\Sigma \left[\Delta H_f\textdegree{}(\text{Reactants})]\right[/tex]. Note the order: product minus reactants. Keep all the signs as is in these calculations.[tex]\Delta H_\text{f}\textdegree{} = 0[/tex] for the most stable allotrope of each elements under their standard state. For example,
[tex]\text{O}_2[/tex] (not [tex]\text{O}_3[/tex] ozone) is the most stable allotrope of oxygen under STP. [tex]\text{O}_2[/tex] is a gas under STP.As a result, [tex]\Delta H_\text{f}\textdegree{} = 0[/tex] for [tex]\text{O}_2\;(g)[/tex]. Note the gaseous state symbol. This value is implied such that it's not provided in the question.
For this reaction:
[tex]\Sigma \left[\Delta H_f\textdegree{}(\textbf{Products})]\right = 4 \times (+33.2) + 6\times (-285.83) = -1582.18\;\text{kJ}\cdot\text{mol}^{-1}[/tex].
[tex]\Sigma \left[\Delta H_f\textdegree{}(\textbf{Reactants})]\right = 4 \times (-46.11) + 7\times 0 = -184.44 \;\text{kJ}\cdot\text{mol}^{-1}[/tex].
Apply the equation:
[tex]\begin{aligned} \Delta H_\text{rxn} &= \Sigma \left[\Delta H_f\textdegree{}(\textbf{Products})]\right - \Sigma \left[\Delta H_f\textdegree{}(\textbf{Reactants})]\right\\ &= -1582.18\;\text{kJ}\cdot\text{mol}^{-1} - (-184.44 \;\text{kJ}\cdot\text{mol}^{-1})\\ &= -1397.74\;\text{kJ}\cdot\text{mol}^{-1}\end{aligned}[/tex].
The enthalpy of the given reaction is close to -1766 kJ/mol rxn. This is calculated by subtracting the total enthalpy of formation of the reactants from that of the products.
Explanation:To determine the enthalpy of the given reaction, we need to calculate the total enthalpy of formation of the products and subtract the total enthalpy of formation of the reactants from it.
The general formula for calculating enthalpy (∆H) in a reaction is: ∆H = Σ ∆Hf(products) - Σ ∆Hf(reactants).
For the products: 4 mol of NO2(g) and 6 mol of H2O(l), ∆Hf = [4(-33.2 kJ/mol) + 6(-285.83 kJ/mol)] = -1980.92 kJ.
For the reactants: 4 mol of NH3(g) and 7 mol of O2(g), ∆Hf = 4(-46.11 kJ/mol) = -184.44 kJ (Note: The enthalpy of elements in their standard state, like O2(g), is zero).
Finally, the enthalpy of the reaction (∆H) = -1980.92 kJ - (-184.44 kJ) = -1796.48 kJ. Hence the closest option is -1766 kJ/mol rxn.
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What is the molarity of a solution containing 100 moles of NaCl dissolved in 10 liters of water?
2 mol/L
10 mol/L
0.5 mol/L
5 mol/L
Answer:
10 mol/L
Explanation:
Molarity or concentration is given by the formula;
Molarity = Number of moles/Volume in Liters
In this case; number of moles = 100 and Volume = 10 L
Therefore;
Molarity = 100 moles/10 L
= 10 mol/L
The answer is 10 mol/L
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The mass of cobalt-60 in a sample decreased from 0.800g to 0.200g over a period of 10.5 years. From this information, calculate the half-life of cobalt-60.
The half-life of cobalt-60, based on the provided information and the calculation method where the sample mass decreases to a quarter over two half-lives (10.5 years), is confirmed to be 5.27 years. This example illustrates how the half-life concept helps in understanding the decay rate of radioactive isotopes.
Explanation:To calculate the half-life of cobalt-60 given that the mass of a cobalt-60 sample decreased from 0.800g to 0.200g over a period of 10.5 years, we use the concept of half-lives. The question implies that the sample underwent two half-lives for its mass to decrease to 0.200g from 0.800g.
Here's why: after one half-life, the mass would decrease to 0.400g (half of 0.800g), and after another half-life, it would decrease to 0.200g (half of 0.400g), totaling a decrease over two half-lives.
Given the provided information that the half-life of cobalt-60 is 5.27 years, this aligns perfectly with our calculation method. After 10.54 years (which is approximately the given time span of 10.5 years), two half-lives would have passed, confirming the half-life of cobalt-60 as 5.27 years.
This demonstrates a practical application of understanding radioactive decay and the significance of half-life in measuring how quickly unstable isotopes decline to half their original amount.
What is the molecular formula for ammonium nitrate?
NH4NO3 is the molecular formula
The molecular formula for ammonium nitrate is NH4NO3. It is a salt derived from the reaction of ammonia (NH3) and nitric acid (HNO3), resulting in the formation of the ammonium ion (NH4+) and the nitrate ion (NO3-).
Explanation:The molecular formula for ammonium nitrate is NH4NO3. This compound is a salt of ammonia (NH3) and nitric acid (HNO3). The formula can be deduced from the process by which it is formed: The ammonia molecule's nitrogen atom (N) combines with three hydrogen atoms (H) to form NH3, and the nitric acid molecule's nitrogen (N) combines with one hydrogen (H), one nitrogen (N), and three oxygen (O) atoms to form HNO3.
In a reaction between these two compounds, the hydrogen in the nitric acid becomes attached to the nitrogen in the ammonia, forming the ammonium ion (NH4+), and the remaining NO3 molecule forms the nitrate ion (NO3-). These two ions come together to form ammonium nitrate.
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The most basic general formula for the amide is: RNCO RHCN RCONH2 NaNH2
Answer:
NaNH2 is the answer
Explanation:
Answer: Option (c) is the correct answer.
Explanation:
An organic compound that contains the functional group "[tex]-CONH_{2}[/tex]" is known as an amide.
General chemical formula of an amide is [tex]RCONH_{2}[/tex], where R can be alkyl or aryl group.
For example, [tex]CH_{3}CH_{2}CONH_{2}[/tex] is a primary amide whose name is ethanamide.
A compound that contains a functional group "-NCO" is known as an isocyanate group.
And, "-CN" functional group is known as cyanate group.
[tex]NaNH_{2}[/tex] is a compound called sodamide and it is a specific formula.
Hence, we can conclude that the most basic general formula for the amide is [tex]RCONH_{2}[/tex].
a sample of 3.0 mols of hydrogren gas has a volume of 75ML. 1.5 mols of hydrogen is added if the pressure and temperature remains constant ,calculate the final volume of the gas?
Answer:
37.5 mL.
Explanation:
We can use the general law of ideal gas: PV = nRT.where, P is the pressure of the gas in atm.
V is the volume of the gas in L.
n is the no. of moles of the gas in mol.
R is the general gas constant,
T is the temperature of the gas in K.
If P and T are constant, and have different values of n and V:(V₁n₂) = (V₂n₁)
Knowing that:
V₁ = 75 mL, n₁ = 3.0 mol,
V₂ = ??? mL, n₂ = 1.5 mol.
Applying in the above equation(V₁n₂) = (V₂n₁)
∴ V₂ = (V₁n₂)/n₁ = (75 mL)(1.5 mol)/(3.0 mol) = 37.5 mL.
Answer:
4.5 ML that is what i think
Explanation:
How can you make a saturated solution from a supersaturated solution?
Answer:
warming up the solution.
Explanation:
A saturated solution is a chemical solution containing the maximum concentration of a solute dissolved in the solvent. The additional solute will not dissolve in a saturated solution.Supersaturated solution is a solution that contains more of the dissolved material than could be dissolved by the solvent under normal circumstances.A saturated solution can become supersaturated when it is cooled.Also, we can form a saturated solution from a supersaturated solution via warming up the solution:The solubility of solid solutes in liquid solvents increases as the solvent is warmed up.
A supersaturated solution can be converted back to a saturated solution by perturbing the solution through methods like adding a seed crystal or mechanical agitation, which facilitate the precipitation of excess solute.
Explanation:To turn a supersaturated solution back into a saturated solution, you could either add more solute, warm the solution, or both. In a supersaturated solution, the concentration of solute exceeds its solubility, unbalancing the state of equilibrium and resulting in the precipitation of solutes when disturbed. This happens because the temperature dependence of solubility allows solutions to be supersaturated at an elevated temperature and then cooled to a lower temperature without resulting in solute precipitation.
One method by which you can induce this precipitation is by adding a seed crystal, which serves as a template for the excess solute to crystallize onto. Mechanical agitation is another method that can be used, disturbing the stability and equilibrium of the supersaturated solution and causing the precipitate to form, effectively turning the solution back into a saturated one.
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What heavier element is created when hydrogen atoms fuse together in the sun’s core?
Answer:
Helium is created from hydrogen in the sun's core.
Four hydrogen-1 nuclei fuse to produce
one helium-4 nucleus, two neutrons, two positrons, and two electron neutrinos.Explanation:
Step One:
[tex]{\rm ^1_1 H + ^1_1 H\to ^2_1 H + e^{+}} + v_e[/tex].
Two hydrogen-1 nuclei fuse. One proton will convert to a neutron. The products will be
one hydrogen-2 nucleus, one positron, andone electron neutrino.Step Two:
[tex]\rm ^1_1 H +^2_1 H \to ^3_2 He[/tex].
There are plenty of hydrogen-1 nuclei available in the core of the sun. The hydrogen-2 nucleus from step one will fuse with a hydrogen-1 nucleus. The product is
one helium-3 nucleus.Step Three
[tex]\rm ^3_2 He + ^3_2 He \to ^4_2 He + ^1_1 H + ^1_1 H[/tex].
Two helium-3 nuclei from step two react with each other. The products are:
one helium-4 nucleus, andtwo hydrogen-1 nuclei.The overall reaction will be:
[tex]{\rm 6\; ^1_1 H \to ^4_2 He + 2\; ^1_1 H+2\; e^{+}}+v_\text{e}[/tex].
[tex]{\rm 4\; ^1_1 H \to ^4_2 He + 2\; e^{+}} + v_\text{e}[/tex]
In other words, hydrogen nuclei in the core of the sun fuse together to form helium.
Balance the following redox equation using the oxidation-number-change method. Show your work, describing each step.
HNO3 + H2S —-> S + NO + H2O
2HNO3+3H2S ——>2S+4H2O+2NO