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Solving Problems: A Chemistry Handbook
Chemistry: Matter and Change
153
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 15
In the calorimeter, the amount of heat gained by the water equals the
amount of heat lost by the metal sample.
q ϭ q w ϭ q m ϭ 3430 J
Now examine the equation for the heat lost by the metal.
q ϭ c m ϫ m m ϫ ⌬T m
This equation can be rearranged to find the specific heat of the
metal.
c m ϭ
The temperature change for the metal is as follows.
⌬T m ϭ 133°C Ϫ 24.6°C ϭ 108°C
Substitute the known values into the equation for the specific heat of
the metal.
c m ϭ
ϭ
ϭ0.84 J/(g и °C)
Practice Problems
4. A 50.6-g sample of iron metal is heated and put into 104 g of
water at 19.7°C in a calorimeter. If the final temperature of the
iron sample and the water is 24.3°C, what was the temperature
of the iron sample when it was placed in the water?
5. A 77.5-g sample of an unknown solid is heated to 62.5°C and
placed into a calorimeter containing 93 g of water at 23.3°C. If
the final temperature of the solid sample and the water is
26.2°C, what is the specific heat of the solid?
6. If 40.0 g of water at 70.0°C is mixed with 40.0 g of ethanol at
10.0°C, what is the final temperature of the mixture? (Hint: The
heat lost by the water equals the heat gained by the ethanol.
Assume no heat loss to the surroundings.)
Thermochemistry is the study of heat changes that accompany
chemical reactions and phase changes. In thermochemistry, the
system is the reaction or process being studied, and everything
outside the system is called the surroundings. The universe is
defined as the system plus the surroundings.
3430 J
ᎏᎏ
37.8 g ϫ 108°C
q
ᎏᎏ
m m ϫ ⌬T m
q
ᎏᎏ
m m ϫ ⌬T m
Solving Problems: A Chemistry Handbook
Chemistry: Matter and Change
153
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 15
In the calorimeter, the amount of heat gained by the water equals the
amount of heat lost by the metal sample.
q ϭ q w ϭ q m ϭ 3430 J
Now examine the equation for the heat lost by the metal.
q ϭ c m ϫ m m ϫ ⌬T m
This equation can be rearranged to find the specific heat of the
metal.
c m ϭ
The temperature change for the metal is as follows.
⌬T m ϭ 133°C Ϫ 24.6°C ϭ 108°C
Substitute the known values into the equation for the specific heat of
the metal.
c m ϭ
ϭ
ϭ0.84 J/(g и °C)
Practice Problems
4. A 50.6-g sample of iron metal is heated and put into 104 g of
water at 19.7°C in a calorimeter. If the final temperature of the
iron sample and the water is 24.3°C, what was the temperature
of the iron sample when it was placed in the water?
5. A 77.5-g sample of an unknown solid is heated to 62.5°C and
placed into a calorimeter containing 93 g of water at 23.3°C. If
the final temperature of the solid sample and the water is
26.2°C, what is the specific heat of the solid?
6. If 40.0 g of water at 70.0°C is mixed with 40.0 g of ethanol at
10.0°C, what is the final temperature of the mixture? (Hint: The
heat lost by the water equals the heat gained by the ethanol.
Assume no heat loss to the surroundings.)
Thermochemistry is the study of heat changes that accompany
chemical reactions and phase changes. In thermochemistry, the
system is the reaction or process being studied, and everything
outside the system is called the surroundings. The universe is
defined as the system plus the surroundings.
3430 J
ᎏᎏ
37.8 g ϫ 108°C
q
ᎏᎏ
m m ϫ ⌬T m
q
ᎏᎏ
m m ϫ ⌬T m