All of the following statements are true EXCEPT

the sum of the enthalpies of formation of the products in a chemical reaction is defined as the enthalpy of reaction.

Hess' law states that ΔH for an overall reaction is the sum of the ΔH values for the individual equations.

the molar enthalpy of formation of a compound is equal to the enthalpy change when one mole of the compound is formed from elements.

a reaction with a negative enthalpy is exothermic.

the enthalpy of formation of an element in its most stable state is equal to zero.

The initial rates method was used to study the reaction below. 2A + B + C → D + E [A] (mol/L) [B] (mol/L) [C] (mol/L) Δ[D]/Δt (mol/L·s) 0.150 0.250 0.300 1.47 × 106 0.150 0.125 0.300 3.68 × 107 0.150 0.250 0.600 2.94 × 106 0.300 0.125 0.300 7.35 × 107

rate = 5.23 × 104[A] × [B]2 × [C]

rate = 8.71 × 104[A]2 × [B] × [C]

rate = 2.90 × 103[A]2 × [B] × [C]2

rate = 8.71 × 104[A] × [B] × [C]2

Difficult Chemistry Questions And Answers

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Difficult Chemistry Questions And Answers

If 50.0 g of benzene, C₆H₆, at 25.0⁰C absorbs 2.71 kJ of energy in the form of heat, what is the final temperature of the benzene? The specific heat of benzene is 1.72 J/g·⁰C.

If 495 J is required to change the temperature of 12.7 g of sodium chloride from 75.0⁰C to 135 ⁰C, what is the specific heat of sodium chloride?

Water has a specific heat of 4.18 J/g · ⁰C. If 35.0 g of water at 98.8 ⁰C loses 4.94 kJ of heat, what is the final temperature of the water?

When 66.0 g of an unknown metal at 28.5⁰C is placed in 83.0 g H₂O at 78.5⁰C, the water temperature decreases to 75.9⁰C. What is the specific heat capacity of the metal? The specific heat capacity of water is 4.184 J/g⁰C.

A coffee-cup calorimeter contains 10.0 g of water at 59.00⁰C. If 3.00 g gold at 15.20 ⁰C is placed in the calorimeter, what is the final temperature of the water in the calorimeter? The specific heat of water is 4.18 J/g ·⁰C; the specific heat of gold is 0.128 J/g ·⁰C.

When 10.0 g KOH is dissolved in 100.0 g of water in a coffee-cup calorimeter, the temperature rises from 25.18 ⁰C to 47.53 ⁰C. What is the enthalpy change per gram of KOH dissolved in the water? Assume that the solution has a specific heat capacity of 4.18 J/g⁰C.

10.0 g of ice at 0.00 ⁰C is mixed with 25.0 g of water at 35.00⁰C in a coffee-cup calorimeter. What is the final temperature of the mixture? The specific heat of water is 4.18 J/g ⁰C; the heat of fusion of water is 333 J/g.

All of the following statements are true EXCEPT

Determine the heat of reaction for the combustion of ammonia, 4NH₃(g) + 7O₂(g) → 4NO₂(g) + 6H₂O(l) using molar enthalpies of formation. NH3(g) –45.9 NO2(g) +33.1 H2O(l) –285.8

The standard molar enthalpy of formation of NH₃(g) is –45.9 kJ/mol. What is the enthalpy change if 9.51 g N₂(g) and 1.96 g H₂(g) react to produce NH₃(g)?

For the reaction below, relate the rate of disappearance of hydrogen to the rate of formation of ammonia. N₂(g) + 3H₂(g) → 2NH₃(g)

The rate of reaction for the formation of carbon monoxide is measured at 1.24 mol/L·hr. What is the rate of formation of carbon monoxide in units of mol/L·s? CH₃CHO(g) → CH₄(g) + CO(g)

For the reaction below, if the rate of appearance of Br₂ is 0.180 mol/L·s, what is the rate of disappearance of NOBr? 2NOBr(g) → 2NO(g) + Br₂(g)

Dinitrogen pentaoxide decomposes nitrogen dioxide and oxygen according to the following balanced chemical equation and rate expression. 2N₂O₅(g) → 4NO₂(g) + O₂(g) rate = k[N₂O₅] What is the overall reaction order?

The initial rates method was used to study the reaction below. A + 3B =2C [A] (mol/L) [B] (mol/L) -D[A]/Dt (mol/L×s) 0.210 0.150 3.41 x 10^3 0.210 0.300 1.36 x 10^2 0.420 0.300 2.73 x 10^-2

The initial rates method was used to study the reaction below. 2A + B + C → D + E [A] (mol/L) [B] (mol/L) [C] (mol/L) Δ[D]/Δt (mol/L·s) 0.150 0.250 0.300 1.47 × 10^6 0.150 0.125 0.300 3.68 × 10^7 0.150 0.250 0.600 2.94 × 10^6 0.300 0.125 0.300 7.35 × 10^7

The rate constant of a first-order decomposition reaction is 0.0147 s^–1. If the initial concentration of reactant is 0.178 M, what is the concentration of reactant after 30.0 seconds?

The rate constant for the decomposition of cyclobutane is 2.08 × 10^-2 s^-1 at high temperatures. C₄H₈(g) → 2C₂H₄(g) How many seconds are required for an initial concentration of 0.100 M C₄H₈(g) to decrease to 0.0450 M?

The reaction A → B follows first-order kinetics with a half-life of 21.7 hours. If the concentration of A is 0.023 M after 48.0 hours, what is the initial concentration of A?

For the first-order reaction below, the concentration of product B after 24.2 seconds is 0.322 M. If k = 8.75 × 10^-2 s^-1, what was the initial concentration of A? A → 2B rate = k[A]

For the second-order reaction below, the rate constant of the reaction is 9.4 × 10^–3 M^–1s^–1. How long (in seconds) is required to decrease the concentration of A from 2.16 M to 0.40 M? 2A → B rate = k[A]²

For the first-order reaction below, the initial concentration of A is 0.80 M. What is the half-life of the reaction if the concentration of A decreases to 0.10 M in 54 seconds? A → B rate = k[A]

Which of the following statements is/are CORRECT? 1. Product concentrations appear in the numerator of an equilibrium constant expression. 2. A reaction favors the formation of products if K >> 1. 3. Stoichiometric coefficients are used as exponents in an equilibrium constant expression.

Use the equilibrium constants for the following reactions at 700 ⁰C 2SO₂(g) + O₂(g) 2SO₃(g) K₁ = 4.8 2NO(g) + O₂(g) 2NO₂(g) K₂ = 16 to determine the equilibrium constant for the following reaction. SO₃(g) + NO(g) SO₂(g) + NO₂(g)

Nitrosyl chloride decomposes according to the chemical equation below. 2NOCl(g) 2NO(g) + Cl₂(g) A pressure of 0.320 atm of nitrosyl chloride is sealed in a flask and allowed to reach equilibrium. If 22.6% of the NOCl decomposes, what is the equilibrium constant for the reaction?

For the system CO(g) + H₂O(g) CO₂(g) + H₂(g) K is 1.6 at 900 K. If 0.400 atm CO(g) and 0.400 atm H₂O(g) are combined in a sealed flask, what is the partial equilibrium pressure of CO₂(g)?

Which of the following may change the ratio of products to reactants in an equilibrium mixture for a chemical reaction involving gaseous species? 1. Increasing the temperature. 2. Adding a catalyst. 3. Adding gaseous reactants.

Calcium carbonate decomposes to calcium oxide and carbon dioxide. CaCO₃(s) CaO(s) + CO₂(g) ΔH⁰ = 179 kJ The equilibrium constant for this reaction is 9.7 × 10^24 at 298 K. What is the equilibrium constant at 575 K? (R = 8.31 J/mol·K)

Difficult Chemistry Questions And Answers

If 50.0 g of benzene, C6H6, at 25.00C absorbs 2.71 kJ of energy in the form of heat, what is the final temperature of the benzene? The specific heat of benzene is 1.72 J/g·0C.

If 495 J is required to change the temperature of 12.7 g of sodium chloride from 75.00C to 135 0C, what is the specific heat of sodium chloride?

Water has a specific heat of 4.18 J/g · 0C. If 35.0 g of water at 98.8 0C loses 4.94 kJ of heat, what is the final temperature of the water?

When 66.0 g of an unknown metal at 28.50C is placed in 83.0 g H2O at 78.50C, the water temperature decreases to 75.90C. What is the specific heat capacity of the metal? The specific heat capacity of water is 4.184 J/g0C.

A coffee-cup calorimeter contains 10.0 g of water at 59.000C. If 3.00 g gold at 15.20 0C is placed in the calorimeter, what is the final temperature of the water in the calorimeter? The specific heat of water is 4.18 J/g ·0C; the specific heat of gold is 0.128 J/g ·0C.

When 10.0 g KOH is dissolved in 100.0 g of water in a coffee-cup calorimeter, the temperature rises from 25.18 0C to 47.53 0C. What is the enthalpy change per gram of KOH dissolved in the water? Assume that the solution has a specific heat capacity of 4.18 J/g0C.

10.0 g of ice at 0.00 0C is mixed with 25.0 g of water at 35.000C in a coffee-cup calorimeter. What is the final temperature of the mixture? The specific heat of water is 4.18 J/g 0C; the heat of fusion of water is 333 J/g.

All of the following statements are true EXCEPT

Determine the heat of reaction for the combustion of ammonia, 4NH3(g) + 7O2(g) → 4NO2(g) + 6H2O(l) using molar enthalpies of formation. NH3(g) –45.9 NO2(g) +33.1 H2O(l) –285.8

The standard molar enthalpy of formation of NH3(g) is –45.9 kJ/mol. What is the enthalpy change if 9.51 g N2(g) and 1.96 g H2(g) react to produce NH3(g)?

For the reaction below, relate the rate of disappearance of hydrogen to the rate of formation of ammonia. N2(g) + 3H2(g) → 2NH3(g)

The rate of reaction for the formation of carbon monoxide is measured at 1.24 mol/L·hr. What is the rate of formation of carbon monoxide in units of mol/L·s? CH3CHO(g) → CH4(g) + CO(g)

For the reaction below, if the rate of appearance of Br2 is 0.180 mol/L·s, what is the rate of disappearance of NOBr? 2NOBr(g) → 2NO(g) + Br2(g)

Dinitrogen pentaoxide decomposes nitrogen dioxide and oxygen according to the following balanced chemical equation and rate expression. 2N2O5(g) → 4NO2(g) + O2(g) rate = k[N2O5] What is the overall reaction order?

The initial rates method was used to study the reaction below. A + 3B =2C [A] (mol/L) [B] (mol/L) -D[A]/Dt (mol/L×s) 0.210 0.150 3.41 x 10^3 0.210 0.300 1.36 x 10^2 0.420 0.300 2.73 x 10^-2

The initial rates method was used to study the reaction below. 2A + B + C → D + E [A] (mol/L) [B] (mol/L) [C] (mol/L) Δ[D]/Δt (mol/L·s) 0.150 0.250 0.300 1.47 × 106 0.150 0.125 0.300 3.68 × 107 0.150 0.250 0.600 2.94 × 106 0.300 0.125 0.300 7.35 × 107

The rate constant of a first-order decomposition reaction is 0.0147 s–1. If the initial concentration of reactant is 0.178 M, what is the concentration of reactant after 30.0 seconds?

The rate constant for the decomposition of cyclobutane is 2.08 × 10-2 s-1 at high temperatures. C4H8(g) → 2C2H4(g) How many seconds are required for an initial concentration of 0.100 M C4H8(g) to decrease to 0.0450 M?

The reaction A → B follows first-order kinetics with a half-life of 21.7 hours. If the concentration of A is 0.023 M after 48.0 hours, what is the initial concentration of A?

For the first-order reaction below, the concentration of product B after 24.2 seconds is 0.322 M. If k = 8.75 × 10-2 s-1, what was the initial concentration of A? A → 2B rate = k[A]

For the second-order reaction below, the rate constant of the reaction is 9.4 × 10–3 M–1s–1. How long (in seconds) is required to decrease the concentration of A from 2.16 M to 0.40 M? 2A → B rate = k[A]2

For the first-order reaction below, the initial concentration of A is 0.80 M. What is the half-life of the reaction if the concentration of A decreases to 0.10 M in 54 seconds? A → B rate = k[A]

Which of the following statements is/are CORRECT? 1. Product concentrations appear in the numerator of an equilibrium constant expression. 2. A reaction favors the formation of products if K >> 1. 3. Stoichiometric coefficients are used as exponents in an equilibrium constant expression.

Use the equilibrium constants for the following reactions at 700 0C 2SO2(g) + O2(g) 2SO3(g) K1 = 4.8 2NO(g) + O2(g) 2NO2(g) K2 = 16 to determine the equilibrium constant for the following reaction. SO3(g) + NO(g) SO2(g) + NO2(g)

Nitrosyl chloride decomposes according to the chemical equation below. 2NOCl(g) 2NO(g) + Cl2(g) A pressure of 0.320 atm of nitrosyl chloride is sealed in a flask and allowed to reach equilibrium. If 22.6% of the NOCl decomposes, what is the equilibrium constant for the reaction?

For the system CO(g) + H2O(g) CO2(g) + H2(g) K is 1.6 at 900 K. If 0.400 atm CO(g) and 0.400 atm H2O(g) are combined in a sealed flask, what is the partial equilibrium pressure of CO2(g)?

Which of the following may change the ratio of products to reactants in an equilibrium mixture for a chemical reaction involving gaseous species? 1. Increasing the temperature. 2. Adding a catalyst. 3. Adding gaseous reactants.

Calcium carbonate decomposes to calcium oxide and carbon dioxide. CaCO3(s) CaO(s) + CO2(g) ΔH0 = 179 kJ The equilibrium constant for this reaction is 9.7 × 1024 at 298 K. What is the equilibrium constant at 575 K? (R = 8.31 J/mol·K)

If 50.0 g of benzene, C₆H₆, at 25.0⁰C absorbs 2.71 kJ of energy in the form of heat, what is the final temperature of the benzene? The specific heat of benzene is 1.72 J/g·⁰C.

If 495 J is required to change the temperature of 12.7 g of sodium chloride from 75.0⁰C to 135 ⁰C, what is the specific heat of sodium chloride?

Water has a specific heat of 4.18 J/g · ⁰C. If 35.0 g of water at 98.8 ⁰C loses 4.94 kJ of heat, what is the final temperature of the water?

When 66.0 g of an unknown metal at 28.5⁰C is placed in 83.0 g H₂O at 78.5⁰C, the water temperature decreases to 75.9⁰C. What is the specific heat capacity of the metal? The specific heat capacity of water is 4.184 J/g⁰C.

A coffee-cup calorimeter contains 10.0 g of water at 59.00⁰C. If 3.00 g gold at 15.20 ⁰C is placed in the calorimeter, what is the final temperature of the water in the calorimeter? The specific heat of water is 4.18 J/g ·⁰C; the specific heat of gold is 0.128 J/g ·⁰C.

When 10.0 g KOH is dissolved in 100.0 g of water in a coffee-cup calorimeter, the temperature rises from 25.18 ⁰C to 47.53 ⁰C. What is the enthalpy change per gram of KOH dissolved in the water? Assume that the solution has a specific heat capacity of 4.18 J/g⁰C.

10.0 g of ice at 0.00 ⁰C is mixed with 25.0 g of water at 35.00⁰C in a coffee-cup calorimeter. What is the final temperature of the mixture? The specific heat of water is 4.18 J/g ⁰C; the heat of fusion of water is 333 J/g.

Determine the heat of reaction for the combustion of ammonia, 4NH₃(g) + 7O₂(g) → 4NO₂(g) + 6H₂O(l) using molar enthalpies of formation. NH3(g) –45.9 NO2(g) +33.1 H2O(l) –285.8

The standard molar enthalpy of formation of NH₃(g) is –45.9 kJ/mol. What is the enthalpy change if 9.51 g N₂(g) and 1.96 g H₂(g) react to produce NH₃(g)?

For the reaction below, relate the rate of disappearance of hydrogen to the rate of formation of ammonia. N₂(g) + 3H₂(g) → 2NH₃(g)

The rate of reaction for the formation of carbon monoxide is measured at 1.24 mol/L·hr. What is the rate of formation of carbon monoxide in units of mol/L·s? CH₃CHO(g) → CH₄(g) + CO(g)

For the reaction below, if the rate of appearance of Br₂ is 0.180 mol/L·s, what is the rate of disappearance of NOBr? 2NOBr(g) → 2NO(g) + Br₂(g)

Dinitrogen pentaoxide decomposes nitrogen dioxide and oxygen according to the following balanced chemical equation and rate expression. 2N₂O₅(g) → 4NO₂(g) + O₂(g) rate = k[N₂O₅] What is the overall reaction order?

The initial rates method was used to study the reaction below. 2A + B + C → D + E [A] (mol/L) [B] (mol/L) [C] (mol/L) Δ[D]/Δt (mol/L·s) 0.150 0.250 0.300 1.47 × 10^6 0.150 0.125 0.300 3.68 × 10^7 0.150 0.250 0.600 2.94 × 10^6 0.300 0.125 0.300 7.35 × 10^7

The rate constant of a first-order decomposition reaction is 0.0147 s^–1. If the initial concentration of reactant is 0.178 M, what is the concentration of reactant after 30.0 seconds?

The rate constant for the decomposition of cyclobutane is 2.08 × 10^-2 s^-1 at high temperatures. C₄H₈(g) → 2C₂H₄(g) How many seconds are required for an initial concentration of 0.100 M C₄H₈(g) to decrease to 0.0450 M?

For the first-order reaction below, the concentration of product B after 24.2 seconds is 0.322 M. If k = 8.75 × 10^-2 s^-1, what was the initial concentration of A? A → 2B rate = k[A]

For the second-order reaction below, the rate constant of the reaction is 9.4 × 10^–3 M^–1s^–1. How long (in seconds) is required to decrease the concentration of A from 2.16 M to 0.40 M? 2A → B rate = k[A]²

Use the equilibrium constants for the following reactions at 700 ⁰C 2SO₂(g) + O₂(g) 2SO₃(g) K₁ = 4.8 2NO(g) + O₂(g) 2NO₂(g) K₂ = 16 to determine the equilibrium constant for the following reaction. SO₃(g) + NO(g) SO₂(g) + NO₂(g)

Nitrosyl chloride decomposes according to the chemical equation below. 2NOCl(g) 2NO(g) + Cl₂(g) A pressure of 0.320 atm of nitrosyl chloride is sealed in a flask and allowed to reach equilibrium. If 22.6% of the NOCl decomposes, what is the equilibrium constant for the reaction?

For the system CO(g) + H₂O(g) CO₂(g) + H₂(g) K is 1.6 at 900 K. If 0.400 atm CO(g) and 0.400 atm H₂O(g) are combined in a sealed flask, what is the partial equilibrium pressure of CO₂(g)?

Calcium carbonate decomposes to calcium oxide and carbon dioxide. CaCO₃(s) CaO(s) + CO₂(g) ΔH⁰ = 179 kJ The equilibrium constant for this reaction is 9.7 × 10^24 at 298 K. What is the equilibrium constant at 575 K? (R = 8.31 J/mol·K)