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Hess's Law and Bomb Calorimetry

Total questions: 15

Worksheet time: 4hrs 45mins

Name
Class
Date
1.

Using the equations below:

C(s) + O2(g) → CO2(g) ∆H = –390 kJ

Mn(s) + O2(g) → MnO2(s) ∆H = –520 kJ

what is ∆H (in kJ) for the following reaction?

MnO2(s) + C(s) → Mn(s) + CO2(g)

a)

910

b)

130

c)

-130

d)

-910

2.

Using the equations below

Cu(s) + 1/2O2(g) → CuO(s) ∆H = –156 kJ

2Cu(s) + O2(g) → Cu2O(s)H = –170 kJ

what is the value of ∆H (in kJ) for the following reaction?

2CuO(s) → Cu2O(s) + 1/2O2(g)

a)

142

b)

15

c)

-15

d)

-142

3.

Consider the following equations.

Mg(s) + O2(g) → MgO(s)H = –602 kJ

H2(g) + O2(g) → H2O(g)H = –242 kJ

What is the ∆H value (in kJ) for the following reaction?

MgO(s) + H2(g) → Mg(s) + H2O(g)

a)

-844

b)

-360

c)

+360

d)

+844

4.

The following equations show the oxidation of carbon and carbon monoxide to carbon dioxide.

C(s) +O2(g) CO2(g) ΔH = –x kJ mol–1

CO(g) + O2(g) CO2(g) ΔH = –y kJ mol–1

What is the enthalpy change, in kJ mol–1, for the oxidation of carbon to carbon monoxide?

C(s) + O2(g) → CO(g)

a)

x + y

b)

-x - y

c)

y - x

d)

x - y

5.

Which of the following statements are true for the reaction:

SO2(g) + 1/2O2(g) ↔ SO3(g)

ΔH = –92 kJ mol-1

Where ↔ indicates that the reaction can proceed in the forward and the reverse direction.

a)

The forward and reverse reaction both produce 92 kJ of energy.

b)

Oxidizing 2 moles of SO2 would produce twice as much energy.

c)

The reverse reaction has an enthalpy of +92 kJ mol-1.

d)

Collecting the SO3 produced in the liquid state would not change the measured enthalpy.

6.

The standard enthalpy change of formation values of two oxides of phosphorus are:

P4(s) + 3O2(g) → P4O6(s) ΔHf = –1600 kJ mol–1

P4(s) + 5O2(g) → P4O10(s) ΔHf = –3000 kJ mol–1

What is the enthalpy change, in kJ mol–1, for the reaction below?

P4O6(s) + 2O2(g) → P4O10(s)

a)

+4600

b)

+1400

c)

–1400

d)

–4600

7.
In an endothermic reaction the system is releasing energy.
a)
True
b)
False
c)
Sometimes
8.

The enthalpies of combustion of C(s), H2(g) and C4H9OH(l) (in kJmol-1) are as follows   C(s) + O2(g)   --->  CO2(g)   ∆H=a H2(g) + ½O2(g)   --->   H2O(l)  ∆H=b C4H9OH(l) + 6O2(g)   --->   4CO2(g) + 5H2O(l)  ∆H=c

What is the enthalpy change for the reaction shown below?   4C(g) + 5H2(l) + ½O2(g)   --->   C4H9OH(l)

a)
c – 4a – 5b
b)
2a + 10b - c
c)
4a + 5b - c
d)
2a + 5b + c
9.

If N2 (g) + 2O2 (g) \longrightarrow   2NO2(g) has a ΔHrxn \Delta H_{rxn\ }  = 68, then what is the ΔHrxn\Delta H_{rxn}  if you reverse the reaction?

a)

86 kJ

b)

- 86 kJ

c)

68 kJ

d)

-68 kJ

10.

How much energy is required to turn 1 mole of N2O4(g) into 2 moles N & 4 moles O(g)?

a)

1933 kJ

b)

-1875 kJ

c)

- 1933 kJ

d)

1875 kJ

11.
a)

-824.2

b)
-202.3
c)
-296.1
d)
-233.0
12.
a)
-233
b)
-11.3
c)
-805
d)
-226
13.

The enthalpies of combustion of C(s), H2(g) and C4H9OH(l) (in kJmol-1) are as follows

C(s) + O2(g) -> CO2(g) ∆H=a

H2(g) + ½O2(g) -> H2O(l) ∆H=b

C4H9OH(l) + 6O2(g) -> 4CO2(g) + 5H2O(l) ∆H=c

What is the enthalpy change for the reaction shown below?

4C(g) + 5H2(l) + ½O2(g) -> C4H9OH(l)

a)

c – 4a – 5b

b)

4a + 5b - c

c)

2a + 10b - c

d)

2a + 5b + c

14.
For the formula:
 Q= m c ∆T
The  units for specific heat are:
a)
g /J C
b)
°C/g J
c)
kJ/g
d)
J/g°C
15.
A 2.200 g sample of quinone (C6H4O2) is burned in a bomb calorimeter whose total heat capacity is 7.854 kJ/°C.  The temperature of the calorimeter increases from 23.44°C to 30.57°C.  What is the heat of combustion per mole of quinone?
a)

-2745 kJ/mol

b)
-56.0 kJ/mol
c)
0.0204 kJ/mol
d)
-25.5 kJ/g