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130 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 13
To determine whether your answer is reasonable, notice that the gas
is being squeezed to a smaller volume, which requires that the pressure be increased. So, your answer is probably correct.
Practice Problems
1. What pressure will be needed to reduce the volume of 77.4 L of
helium at 98.0 kPa to a volume of 60.0 L?
2. A 250.0-mL sample of chlorine gas is collected when the barometric pressure is 105.2 kPa. What is the volume of the sample
after the barometer drops to 100.3 kPa?
3. A weather balloon contains 59.5 L of helium at sea level, where
the atmospheric pressure is 101.3 kPa. The balloon is released
from a 4000-m mountaintop where the pressure is 61.7 kPa.
What is the volume of the balloon when it is released?
4. Meteorologists want the balloon in problem 3 to float at an altitude of 35,000 m where the pressure is 575 Pa. What volume
will the balloon have at that altitude?
Charles’s Law When the temperature of a sample of gas is
increased and the volume is free to change, the pressure of the gas
does not increase. Instead, the volume of the gas increases in proportion to the increase in Kelvin temperature. This observation is
Charles’s law, which can be stated mathematically as follows.
ϭ
Example Problem 13-2
Applying Charles’s Law
A weather balloon contains 5.30 kL of helium gas when the temperature is 12 °C. At what temperature will the balloon’s volume have
increased to 6.00 kL?
Start by converting the given temperature to kelvins.
T 1 ϭ (12 ϩ 273) K ϭ 285 K
Next, solve the Charles’s law equation for the new temperature, T 2 .
ϭ
;
V 1 T 2 ϭ V 2 T 1 ;
T 2 ϭ T 1
V 2
ᎏ
V 1
V 2
ᎏ
T 2
V 1
ᎏ
T 1
V 2
ᎏ
T 2
V 1
ᎏ
T 1
▲
130 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 13
To determine whether your answer is reasonable, notice that the gas
is being squeezed to a smaller volume, which requires that the pressure be increased. So, your answer is probably correct.
Practice Problems
1. What pressure will be needed to reduce the volume of 77.4 L of
helium at 98.0 kPa to a volume of 60.0 L?
2. A 250.0-mL sample of chlorine gas is collected when the barometric pressure is 105.2 kPa. What is the volume of the sample
after the barometer drops to 100.3 kPa?
3. A weather balloon contains 59.5 L of helium at sea level, where
the atmospheric pressure is 101.3 kPa. The balloon is released
from a 4000-m mountaintop where the pressure is 61.7 kPa.
What is the volume of the balloon when it is released?
4. Meteorologists want the balloon in problem 3 to float at an altitude of 35,000 m where the pressure is 575 Pa. What volume
will the balloon have at that altitude?
Charles’s Law When the temperature of a sample of gas is
increased and the volume is free to change, the pressure of the gas
does not increase. Instead, the volume of the gas increases in proportion to the increase in Kelvin temperature. This observation is
Charles’s law, which can be stated mathematically as follows.
ϭ
Example Problem 13-2
Applying Charles’s Law
A weather balloon contains 5.30 kL of helium gas when the temperature is 12 °C. At what temperature will the balloon’s volume have
increased to 6.00 kL?
Start by converting the given temperature to kelvins.
T 1 ϭ (12 ϩ 273) K ϭ 285 K
Next, solve the Charles’s law equation for the new temperature, T 2 .
ϭ
;
V 1 T 2 ϭ V 2 T 1 ;
T 2 ϭ T 1
V 2
ᎏ
V 1
V 2
ᎏ
T 2
V 1
ᎏ
T 1
V 2
ᎏ
T 2
V 1
ᎏ
T 1
▲