Gas Laws

Pressure = Force/Area

Pressure in a gas is caused by the collisions of gas molecules with the walls of the container. The molecules are constantly moving in random directions and exert a force when they collide with a wall. Pressure is the result of millions of collisions occurring between the Gas molecules and the wall of the container. Faster the molecules move, the more force they will exert and cause an increase in pressure.

There are many units of Pressure, we use atmospheres or atm in Chemistry.

A certain flexible weather balloon contains 5.9 L of helium gas. Initially, the temperature is 20.4^oC and the barometric pressure is 560.6 torr. The balloon then is taken to the top of Pike’s Peak, where the pressure is 400 torr and the temperature is 9.7^oC. What is the new volume of the balloon at the top of Pikes Peak?

Some text here about the topic of discussion

​560.6 x 5.9 = 400 x V2

293.4 282.7​

3307.54 = 400 x V2

293.4 282.7​

V2 = 7.97 L​

If we are given only one value of P, V or T, we are talking about the ideal gas law.

P = atm, V = L, T = K, R = 0.0821

n = number of moles of a gas.

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You can plug the values in and solve for the unknown variable.

Make sure to convert all values into proper units.​

​A Flask with 5.9 L of volume at 6.1 psi Pressure contains 0.36 moles of a gas. What is the Temperature in the Flask in K?

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P = 6.1 psi = 6.1/14.7 = 0.415 atm

V = 5.9 L

n = moles = 0.36

T = ?

0.415 x 5.9 = 0.36 x 0.0821 x T

T = 82.8 K​