# Chem 2425

30 Questions | Total Attempts: 827  Settings  • 1.
1. 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.
• A.

25.00C

• B.

31.50C

• C.

56.50C

• D.

32.30C

• E.

57.30C

• 2.
2. 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?
• A.

0.866 J/g·0C

• B.

2.60 J/g·0C

• C.

0.650 J/g·0C

• D.

1.15 J/g·0C

• E.

2.83 × 105 J/g·0C

• 3.
3. 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?
• A.

32.00C

• B.

46.20C

• C.

47.20C

• D.

57.20C

• E.

65.0C

• 4.
4. 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.

0.055 J/g· 0C

• B.

0.29 J/g · 0C

• C.

0.69 J/g · 0C

• D.

0.18 J/g · 0C

• E.

2.6 J/g · 0C

• 5.
5. 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.
• A.

55.37 C

• B.

58.60 C

• C.

59.40 C

• D.

60.80 C

• E.

64.19 C

• 6.
6. 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.
• A.

–116 J/g

• B.

–934 J/g

• C.

–1.03 × 103 J/g

• D.

–2.19 × 103 J/g

• E.

–1.03 × 104 J/g

• 7.
7. 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.
• A.

0.00 0C

• B.

2.24 0C

• C.

5.22 0C

• D.

25.0 0C

• E.

47.8 0C

• 8.
8. All of the following statements are true EXCEPT
• A.

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

• B.

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

• C.

A reaction with a negative enthalpy is exothermic.

• D.

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

• E.

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

• 9.
9. 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
• A.

+30.24 kJ

• B.

–206.9 kJ

• C.

–298.6 kJ

• D.

–1398.8 kJ

• E.

–1663.6 kJ

• 10.
10. 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)?
• A.

–10.3 kJ

• B.

–20.7 kJ

• C.

–29.8 kJ

• D.

–43.7 kJ

• E.

–65.6 kJ

• 11.
11. For the reaction below relate the rate of disappearance of hydrogen to the rate of formation of ammonia.         N2(g) + 3H2(g) → 2NH3(g)
• A.

A: +

• B.

B: 3

• C.

C: 1/2

• D.

D: -1/3

• E.

E: -

• 12.
12. 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)
• A.

3.44 × 10-4 mol/L·s

• B.

2.07 × 102 mol/L·s

• C.

1.24 mol/L·s

• D.

74.4 mol/L·s

• E.

4.64 × 103 mol/L·s

• 13.
13. 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)
• A.

–0.360 mol/L·s

• B.

–0.090 mol/L·s

• C.

0.090 mol/L·s

• D.

0.180 mol/L·s

• E.

0.360 mol/L·s

• 14.
14. Dinitrogen pentaoxide decomposes to 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?
• A.

0

• B.

1

• C.

2

• D.

5

• E.

7

• 15.
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
• A.

Rate = 0.515[A] x [B]

• B.

Rate = 0.515[A]^2 x [B]

• C.

Rate = 0.721[A]^2 x [B]

• D.

Rate = 0.721[A] x [B]^2

• E.

Rate = 0.721[A]^2 x [B]^2

• 16.
16. 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
• A.

Rate = 8.71 × 104[A]2 × [B] × [C]

• B.

Rate = 5.23 × 104[A] × [B]2 × [C]

• C.

Rate = 2.90 × 103[A]2 × [B] × [C]2

• D.

Rate = 8.71 × 104[A] × [B] × [C]2

• 17.
17. 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?
• A.

8.72 × 105 M

• B.

0.0645 M

• C.

0.115 M

• D.

0.0785 M

• E.

0.643 M

• 18.
18. 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?
• A.

0.00114 s

• B.

1.07 s

• C.

2.64 s

• D.

38.4 s

• E.

874 s

• 19.
19. 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?
• A.

0.0050 M

• B.

0.051 M

• C.

0.51 M

• D.

0.11 M

• E.

2.0 × 102 M

• 20.
20. 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]
• A.

0.0341 M

• B.

0.183 M

• C.

1.34 M

• D.

2.68 M

• E.

29.3 M

• 21.
21. 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
• A.

2.0 × 10^1 s

• B.

7.8 × 10^1 s

• C.

1.8 × 10^2 s

• D.

1.9 × 10^2 s

• E.

2.2 × 10^2 s

• 22.
22. 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]
• A.

18 s

• B.

24 s

• C.

36 s

• D.

48 s

• E.

51 s

• 23.
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.
• A.

1 only

• B.

2 only

• C.

3 only

• D.

2 and 3

• E.

1, 2, and 3

• 24.
What is the correct equilibrium constant expression for the following reaction?         CO2(g) + 2H2O(g)  CH4(g) + 2O2(g) a.                  b.                  c.              d.
• A.

A

• B.

B

• C.

C

• D.

D

• 25.
25. Write a balanced chemical equation which corresponds to the following equilibrium constant expression.
• A.

1/2N2(g) + 3/2H2(g) = NH3(g)

• B.

N2(g) + 3 H2(g) = 2NH3(g)

• C.

2NH3(g) = N2(g) + 3H2(g)

• D.

NH3(g) = 1/2N2(g) + 3/2H2(g)

• E.

2N2(g) + 6H2(g) = 4NH3(g)

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