Free Printable Thermochemistry

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Thermochemistry

Total questions: 20

Worksheet time: 1hrs 5mins

Name

Class

Date

In an exothermic process heat absorbed.

True

False

A reaction is performed in a beaker with a temperature probe recording the temperature changes of the reaction. If the temperature began at 15.0 degrees Celsius and ended at 27.5 degrees Celsius. If the reaction is our system, is the system endothermic or exothermic?

Exothermic

Endothermic

Refer the the following question:
2N₂ + 3H₂ --> 2NH₃ + 46 kJ
How much energy would be produced if only 1 mol of nitrogen was reacted?

92 kJ

0.143 kJ

23 kJ

15 kJ

What mass of P₄ must be reacted to produce 5905 kJ of energy?
P₄ + 6Cl₂ --> 4PCl₃ + 2439 kJ

25.43 g

563.0 g

2.421 g

300.0 g

H₂ + 2 C + N₂+ 270.3 kJ --> 2 HCN
Is this reaction endothermic or exothermic?

Endothermic

Exothermic

The diagram represents two solids and the temperature of each. What occurs when the two solids are placed in contact with each other?

Heat energy flows from solid A to solid B. Solid A decreases in temperature

Heat energy flows from solid A to solid B. Solid A increases in temperature

Heat energy flows from solid B to solid A. Solid B decreases in temperature.

Heat energy flows from solid B to solid A. Solid B increases in temperature.

The amount of heat energy required to change the temperature of 12 g of gold from 45°C to 15°C is -47 J. What is the specific heat capacity of gold?

0.13 J/(g°C)

17,000 J/(g°C)

1600 J/(g°C)

0.065 J/(g°C)

The graph represents the uniform heating of a substance, starting with the substance as a solid below its melting point. Which line segment listed below represents an increase in potential energy and no change in average kinetic energy?

Line segment AB

Line segment BC

Line segment CD

Line segment EF

A cast iron skillet is used to fry bacon. For optimal frying, the pan must be heated to about 178 ^oC from a room temperature of 22.0 ^oC. It is known that 1.58 x 10⁵ J of heat energy are absorbed by the pan to reach the desired temperature and the specific heat of iron is 0.450 J/g ^oC. What must the mass of the skillet be?

12.7 kg

2.25 kg

110 kg

1.97 kg

10.

Which of the following is an endothermic process?

solid to gas

liquid to solid

solid to liquid

gas to liquid

11.

20 g of water. specific heat of water is 4.18 J/g°C. temperature changes from 25° C to 20° C, how much heat energy (q) moves from the water to the surroundings?

400 J

210 J

80 J

4.18 J

12.

What does temperature measure?

Heat

ºC

Kinetic Energy

Thermal Energy

13.

If two objects have different temperatures, heat will flow from the warmer object to the cooler one UNTIL ____________

one reaches a temperature of zero

they both have an equal temperature

one runs out of energy

14.

What is the specific heat of an unknown substance if 100.0 g of it at 200.0 °C reaches an equilibrium temperature of 27.1 °C when it comes in contact with a calorimeter of water. The water weighs 75. g and had an initial temperature of 20.00 °C? (Specific heat of water is 4.18 J/g°C) (show your work)

0.111 J/g°C

1.29 J/g°C

0.129 J/g°C

22225.85 J

15.

Maria finds that it takes exactly 3,748 Joules to raise the temperature of her coffee from 18°C to 80°C. If the mass of her coffee is 89 g, what is the specific heat of the coffee?

0.526 J/g°C

42.11 J/g°C

60.45 J/g°C

0.679 J/g°C

16.

The specific heat of a substance (C), whose units are J/g°C, is defined as

The number of Joules required to raise the temperature of 1 gram of the substance 1 °C.

The change in temperature when you add 1 Joule of energy.

The number of grams created when the substance cools down 1°C.

How hot or cold that specific amount of substance is.

17.

A sample of water absorbs 50 kJ of energy when it is heated from 20oC to 60oC. The specific heat of water is 4.18J/g oC. What is the mass of the water?

6150.0 g

6.15 g

0.3 g

300 g

18.

If 100 g of aluminum at 145ºC gains 6,800 J of heat, what is the final temperature (T_final) of the aluminum? Aluminum has a specific heat of 0.897 J/gºC. (Q=mcΔT)

-69°C

0.52°C

221°C

19.

How much energy is required to melt 23.0g of water at 0C?

7690J

52000J

14.5J

98.3J

20.

How much energy is required to vaporize 23g of water at 0C?