General chemistry, Chapter 7 – Thermochemistry

What is the SI unit of heat energy?
a) Calorie
b) Joule
c) Watt
d) Electronvolt

b) Joule

Which of the following is an example of an exothermic process?
a) Melting of ice
b) Boiling of water
c) Combustion of gasoline
d) Dissolution of ammonium nitrate in water

c) Combustion of gasoline

In an endothermic reaction:
a) Heat is absorbed from the surroundings
b) Heat is released to the surroundings
c) No heat transfer occurs
d) Energy is converted to mass

a) Heat is absorbed from the surroundings

The first law of thermodynamics is also known as:
a) The law of conservation of energy
b) The law of entropy
c) The law of conservation of mass
d) The law of heat flow

a) The law of conservation of energy

Which quantity remains constant during a process in a bomb calorimeter?
a) Pressure
b) Volume
c) Enthalpy
d) Temperature

b) Volume

The specific heat capacity of water is:
a) 4.18 J/g∘C
b) 1.0 J/g∘C

c) 2.1 J/g∘C
d) 3.0 J/g∘C

a) 4.18 J/g∘C

The heat required to raise the temperature of 10 g of water from 20∘C to 80∘C is:
a) 6.0 kJ
b) 3.0 kJ
c) 2.5 kJ
d) 4.2 kJ

b) 3.0 kJ

Which of the following processes has ΔH<0?
a) Ice melting
b) Water vaporizing
c) Combustion of methane
d) Sublimation of dry ice

c) Combustion of methane

Standard enthalpy of formation for elements in their standard states is:
a) Always positive
b) Always negative
c) Zero
d) Cannot be determined

c) Zero

Which reaction is exothermic?
a) Boiling water
b) Ice freezing
c) Dissolving salt in water
d) Evaporation of alcohol

b) Ice freezing

What is the enthalpy change when 1 mole of a substance burns completely in oxygen?
a) Heat of formation
b) Heat of combustion
c) Heat of fusion
d) Heat of vaporization

b) Heat of combustion

Which substance has the highest specific heat capacity?

a) Aluminum
b) Iron
c) Water
d) Copper

c) Water

A ________ ΔH corresponds to an ________ process.
A) negative, endothermic
B) negative, exothermic
C) positive, exothermic
D) zero, exothermic
E) zero, endothermic

B) negative, exothermic

A chemical reaction that releases heat to the surroundings is said to be ________ and has a
________ ΔH at constant pressure.
A) endothermic, positive
B) endothermic, negative
C) exothermic, negative
D) exothermic, positive
E) exothermic, neutral

C) exothermic, negative

The reaction
4Al (s) + 3O2 (g) → 2 Al2O3 (s) ΔH° = -3351 kJ
is ________, and therefore heat is ________ by the reaction.
A) endothermic, released
B) endothermic, absorbed
C) exothermic, released
D) exothermic, absorbed
E) thermoneutral, neither released nor absorbed

C) exothermic, released

The temperature of a 15-g sample of lead metal increases from 22 °C to 37 °C upon the
addition of 29.0 J of heat. The specific heat capacity of the lead is ________ J/g-K.
A) 7.8
B) 1.9
C) 29
D) 0.13
E) -29

D) 0.13

The temperature of a 35.1 g sample of iron increases from 24.5 *C to 31.8 *C. If the specific
heat of iron is 0.450 J/g-K, how many joules of heat are absorbed?
A) 115 J
B) 0.0936 J
C) -115 J

D) 0.722 J
E) 3.29 J

A) 115 J

Calculate the ΔH°rxn for the decomposition of calcium carbonate to calcium oxide and
carbon dioxide.
ΔH°f [CaCO3(s)] = –1207.7 kJ/mol; ΔH°f [CaO(s)] = –63.9 kJ/mol;
ΔH°f [CO2(g)] = –393.5 kJ/mol
CaCO3(s) → CaO(s) + CO2(g)
A) –2236.1 kJ
B) –1448.5 kJ
C) –179.3 kJ
D) 179.3 kJ
E) 2236.1 kJ

D) 179.3 kJ