All MCAT Physical Resources
Example Questions
Example Question #11 : Gas Laws
What is the temperature of a 1L container at STP after the pressure is doubled?
546K
273K
298K
200K
596K
546K
Using Gay-Lussac's Law, which is , we can find the change in temperature when the pressure is doubled.
Because the problem states that the original conditions were at STP, we know that pressure is 1atm and temperature is 273K. Since pressure and temperature are directly proportional, doubling pressure will also double the temperature. The final temperature will be 546K.
Example Question #472 : Mcat Physical Sciences
of carbon dioxide at an original temperature of is heated to . What is the new volume of the gas?
Remember to convert temperature to Kelvin when using the gas equations.
We will use Charles's Law to calculate the new volume:
Use the given temperatures and initial volume to calculate the final volume.
Example Question #12 : Gas Laws
Which of the following would not cause a decrease in the pressure of a gas in a sealed container?
Increasing the volume of the container
Removing gas particles from the container
Reducing the temperature
Adding moles of a different gas
Adding moles of a different gas
A decrease in pressure means a decrease in gas particle collisions. The only option that would not cause a decrease in collisions is adding moles of a different gas. Even though different molecules are added, there will be greater pressure as particle collisions will be more frequent.
Reducing temperature slows the gas particles, thus decreasing the frequency of collisions. Similarly, increasing the volume of the container and removing particles will cause a decrease in collisions, and subsequent pressure.
Example Question #13 : Gas Laws
A sealed container holds three moles of gas at 1atm and 200K. Its pressure is to 2atm. What will be the resulting temperature in the container?
273K
300K
250K
100K
400K
400K
In the problem, the volume and the number of moles are constant and the temperature and pressure are the only two variables that are changing. Using the ideal gas law we can find that temperature and pressure are directly proportional. When pressure increases by a factor of two, temperature will also increase by a factor of two.
Example Question #14 : Gas Laws
A container holds of oxygen gas at a temperature of . The temperature remains constant and the volume of the container is increased to . What is the final pressure of the gas in terms of the initial pressure, ?
The amount of gas is irrelevant. If the temperature is held constant and the volume is increased by a factor of three, the resulting pressure is decreased by a factor of three according to Boyle’s Law.
Example Question #51 : Fluids And Gases
A gas with an initial volume of and a temperature of is at a pressure of . What is the new pressure if the volume is increased to and the temperature is increased to ?
To solve this problem we use the combined gas law:
Use the given values for the temperature and volume, as well as the initial pressure, to solve for the final pressure.
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