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Enthalpy and Specific Heat

Total questions: 16

Worksheet time: 1hrs 14mins

Name
Class
Date
1.

Calculate the standard molar enthalpy of combustion for ethane, C2H4,

C2H4 (g) + 3 O2(g) --> 2 CO2(g) + 2 H2O(g)

Hf, C2H4 (g) = +52 kJ/mol

Hf, CO2(g) = -394 kJ/mol

Hf, H2O(g) = -242 kJ/mol

a)

-204 kJ

b)

-584 kJ

c)

-679 kJ

d)

-1324 kJ

2.

Calculate the standard enthalpy of combustion for the reaction

SiH4 (g) + 2 O2(g) --> SiO2(g) + 2 H2O(g)

Hf, SiH4 (g) = +34 kJ/mol

Hf, SiO2(g) = -911 kJ/mol

Hf, H2O(g) = -242 kJ/mol

a)

-1187 kJ

b)

-1429 kJ

c)

-1360 kJ

d)

-2219 kJ

3.

Calculate the standard molar enthalpy of combustion for the reaction

2 NO2 (g) + 7 H2(g) --> 2 NH3(g) + 4 H2O(g)

Hf, NO2 (g) = +33 kJ/mol

Hf, NH3(g) = -42 kJ/mol

Hf, H2O(g) = -242 kJ/mol

a)

-1118 kJ

b)

-255 kJ

c)

-808 kJ

d)

-993 kJ

4.

What is the sign of the enthalpy change for an endothermic reaction?

a)

Positive

b)

Cannot be determined

c)

negative

d)

Depends on the pressure

5.

What is the unit for specific heat capacity?

a)

J

b)

kg

c)

K

d)

J/(g ˑoC)

6.

What is the unit for Q in the equation Q = m·Cˑ∆T?

a)

J

b)

kg

c)

K

d)

J/(g ˑoC)

7.

Calculate the standard molar enthalpy of combustion for sucrose, C12H22O11,

C12H22O11 (s) + 6 O2(g) --> 6 CO2(g) + 11 H2O(g)

Hf, C12H22O11 (s) = -2222 kJ/mol

Hf, CO2(g) = -394 kJ/mol

Hf, H2O(g) = -242 kJ/mol

a)

-2804 kJ

b)

-5840 kJ

c)

-6790 kJ

d)

-1324 kJ

8.

Calculate the amount of heat required to heat 357 g of ethylene glycol (antifreeze) from 0oC to 110oC. The specific heat of ethylene glycol is 2.42 J/(gˑK).

a)

16.2 kJ

b)

71.5 kJ

c)

39.3 kJ

d)

95.0 kJ

9.

Calculate the specific heat of Freon-12 if it requires 29.3 joules of heat to raise the temperature of 89.1 g of this gas by 55.0oC.

a)

0.000900 J/(g·K)

b)

0.00598 J/(g·K)

c)

1.67 J/(g·K)

d)

2.83 J/(g·K)

10.

If the specific heat of a substance is low, this means that _____.

a)

It heats up and cools down fast.

b)

All answers are correct.

c)

Has no effect.

d)

It takes longer to heat up and cool down.

11.

Which of the follow represents a normal body temperature of 98.6°F in °Celsius? 5/9 x (0F - 32)

a)

37°C

b)

370°C

c)

72.5°C

d)

72.6°C

12.
What is the transfer of heat by movement of liquids or gases?
a)
Radiation
b)
Convection
c)
Conduction
d)
Heat
13.
What are waves that can transfer heat through the vacuum of empty space?
a)
Electromagnetic waves
b)
Convection
c)
Conduction
d)
Heat
14.
What is the transfer of kinetic energy from one substance to another?
a)
Heat
b)
Energy
c)
Thermal energy
d)
Temperature
15.
A student places a cup of cold water on a counter in a hot room.   After a short time, the student notices that the water in the cup is no longer cold.  Which best explains why the water in the cup is no longer cold?
a)
The coldness of the water transferred to the air, making the water in the cup warmer.
b)
The coldness of the water was conducted to the cup, making the water in the cup warmer.
c)
The heat from the air transferred to the water in the cup, making the water in the cup warmer.
d)
The heat from the air caused the cold water in the cup to condense, making the water warmer.
16.

On a hot summer day, a student dropped an ice cube onto a park bench. Within minutes, the ice cube melted. Which best describes the process the student observed?

a)

radiation

b)

combustion

c)

conduction

d)

convection