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# Thermochemistry & Kinetics (Q).pdf

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McGill University

Chemistry

CHEM 110

Sebastien Breau

Fall

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CHEMISTRY 120
GENERAL CHEMISTRY
MIDTERM 1
Practise Questions on Thermochemistry and Kinetics THESE DATA WILL BE PROVIDED ON THE MIDTERM EXAMINATION
STP: 0°C and 1 atm 1 mol gas at STP: 22.4 L
k = 1.38 x 102J/K 0 K = – 273.15 °C
2
e = 2.718 2 1 Pa = 1 N/m
g = 9.81 m/s 1 atm = 101.3 kPa = 760 Torr
π = 3.14 1 bar = 100,0202Pa = 100 kPa
R = 8.314 J/(mol K) 1 J = 1 kg m /s = 1 kPa L
= 0.08206 L atm /(mol K) 1 mol = 6.02 x 103molecules
P1 1 P2 2 MP MPV
PV nRT nT n T d m
1 1 2 2 RT RT
P 1 N mu 2 e 3 RT u 3RT P hdg
3 V k 2 N A rms M
Integrated Rate Laws:Arrhquastion:
E aRT
Order 0: [A] = [A0 - k eA
k E a 11
ln 2
Order 1: [A] = [A0 e- k 1 1 2
Order 2: 1/[A] = 1/[A]+ kt
0 Standard states for various elements under STP conditions:
Hydrogen: H (g)2 Carbon: C(s, graphite) Nitrogen: N (g2
Oxygen: O (g)Cop Cpue(s) ChloCrilne: (g)
2 2 1) Which of the following is NOT used in the definition of standard enthalpy of formation?
a) elements in standard states
b) heat evolved at constant pressure
c) work at constant volume
d) most stable form
e) none of the above
2) 100.0 g of nickel at 150 °C was placed in 1.00 L of water at 25.0 °C. The final temperature of the
nickel-water mixture was 26.3 °C. What is the specific heat of the nickel?
a) 0.130
b) 0.144
c) 0.439
d) 2.28
e) 0.554
3) 250.0 g of hot coffee at 95.0 °C are placed in a 0.200 kg mug at 20.0 °C. The specific heat of the
coffee is 4.00 J/g °C, while that of the mug is 0.80 J/g °C. Assuming no heat is lost to the
surroundings, what is the final temperature of the system: mug + coffee?
a) 84.7 °C
b) 61.7 °C
c) 76.0 °C
d) 57.5 °C
e) 117 °C
4) If 356 J of work is done by a system while it loses 289 J of heat, what is the value of U?
a) -645 J
b) +67 J
c) +645 J
d) -67 J
e) +134 J 5) 1674 J of heat is absorbed by 25.0 mL of NaOH (d = 1.10 g/mL, specific heat = 4.10 J/g °C). The
temperature of the NaOH goes up how many degrees?
a) 18.0
b) 17.2
c) 14.2
d) 14.8
e) None of the above
6) Given the molar enthalpy of combustion for methanol, CH OH(l), to CO 2(g) and 2 O(l) is -726.6 kJ
3
and the following list of data:
C(graph/2)O → CO(g) ΔH° = -110.5 kJ
2(g)
C(graphit+e) 2(g) → CO (g2 ΔH° = -393.5 kJ
H 2(g) + 1/22 (g) → H O2l) ΔH° = -285.8 kJ
Determine ΔH° for the following reaction:
CO(g) + 2 H 2g) → CH O3(l)
a) -349 kJ
b) -157.8 kJ
c) -128 kJ
d) 157.8 kJ
e) 128 kJ
7) Given:
2 NOCl(g) → 2 NO(g) + Cl (2) ΔH° = +75.56 kJ
2 NO(g) + O 2g) → 2 NO (2) ΔH° = -113.05 kJ
2NO 2g) → N O2 4) ΔH° = -58.03 kJ
Compute ΔH° of N O (g) + Cl (g) → 2 NOCl(g) + O (g) in kJ.
2 4 2 2
a) -246.65
b) +95.52
c) +246.65
d) -95.52
e) None of the above
8) What is the final temperature if 1.785 grams of benzoic acid (7C5 )2is combusted in a bomb
calorimeter with heat capacity of 5.02 kJ/°C and an initial temperature of 24.62 °C? The heat of
combustion of benzoic acid is -26.42 kJ/g.
a) 15.23 °C
b) 51.04 °C
c) 34.01 °C
d) 29.88 °C
e) 31.23 °C 9) Given that ΔH° [CO(g)] = -110.5 kJ/mol and ΔH° [COCl (g)] = -219.1 kJ/mol, what is the enthalpy
f f 2
of reaction for the formation of phosgene, COC2, from carbon monoxide, CO, and chlorine gas,
Cl2(g)?
a) -108.6 kJ
b) -219.1 kJ
c) +110.5 kJ
d) -110.5 kJ
e) +329.6 kJ
10) Determine the enthalpy change in the following equation:
H 2/3 2S(g) + O2(g) → 2/3 SO2(g) + 2/3 2 O(l)
Given:
ΔH° f O2l) = -285.8 kJ/mol
ΔH° H S2g) = -20.63 kJ/mol
f
ΔH° fO (2) = -

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