Boyle’s law, Charles’s law, Avogadro’s law, and the combined gas law establish relationships between the pressure, volume, temperature, and number of moles of a gas sample. These laws are essential for solving gas law problems that involve changes in one or more of these properties.
The Ultimate Guide to Gas Law Problems: Combined Gas Law
Introduction
Gas laws describe the behavior of gases under various conditions. The combined gas law combines three individual gas laws (Boyle’s law, Charles’s law, and Gay-Lussac’s law) into a single equation that can be used to solve a wide range of gas law problems.
Steps to Solve Combined Gas Law Problems
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Identify the Given Information: Note the values provided for the following variables:
- Initial volume (V1)
- Initial pressure (P1)
- Initial temperature (T1) in Kelvin
- Final volume (V2)
- Final pressure (P2)
- Final temperature (T2) in Kelvin
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Convert Temperatures to Kelvin: If the temperatures are not given in Kelvin, convert them using the conversion factor: K = °C + 273.15.
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Plug In the Values: Substitute the given values into the combined gas law equation:
(P1V1) / T1 = (P2V2) / T2 -
Solve for the Unknown: Rearrange the equation to solve for the unknown variable.
Example Problem
A gas occupies 2.5 L at 750 mmHg and 25°C. If the volume changes to 3.2 L and the pressure changes to 650 mmHg, what is the new temperature in °C?
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Given Information:
- V1 = 2.5 L
- P1 = 750 mmHg
- T1 = 25°C = 298 K
- V2 = 3.2 L
- P2 = 650 mmHg
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Convert Temperature: Not needed.
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Plug In Values:
(750 mmHg x 2.5 L) / 298 K = (650 mmHg x 3.2 L) / T2 -
Solve for T2:
- 5625 / 298 = 18.88 mmHg / K * T2
- T2 = 5625 / 18.88 = 298 K
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Convert to °C:
- T2 = 298 K
- T2 = 25°C
Therefore, the new temperature is 25°C.
Tips
- Remember to use absolute temperatures (Kelvin) in the combined gas law equation.
- If you are given more than one unknown variable, solve for one variable at a time by isolating it on one side of the equation.
- Make sure the units are consistent throughout the calculation.
Question 1:
What is the combined gas law?
Answer:
The combined gas law is a formula that combines Boyle’s Law, Charles’ Law, and Gay-Lussac’s Law to describe the relationship between the pressure, volume, temperature, and number of moles of a gas.
Question 2:
How is combined gas law equation useful?
Answer:
The combined gas law equation is useful because it allows us to predict the changes in pressure, volume, temperature, or number of moles of a gas when one of the other variables is changed.
Question 3:
What does combined gas law assume?
Answer:
The combined gas law assumes that the gas is ideal and that the temperature is not too high or too low.
Whew! That was a brain-buster, wasn’t it? But hey, now you know the tricks to tackle any combined gas law problem. Thanks for hanging with me till the end. I appreciate your time and hope you found this article helpful. Remember, practice makes perfect, so keep solving those problems. I’ll be here waiting for you if you have any more questions. Thanks for reading, and see you again soon!