Pressure Help Please

Question

A sample of gas is held at constant temperature. If the volume of this sample of gas is doubled and the number of moles of this sample of gas is doubled, what happens to the pressure of the gas?

Answer 1

Using PV = nRT (ideal gas law) you can add in the following:

Rearrange to solve for P (pressure):

P = nRT / V

Then, double the moles (n) and double the volume (V) with a constant temperature (T):

P = (2n)RT / (2V)

Now, reduce the coefficients in the equation:

P = nRT / V

Since the increase in moles and increase in volume cancel out, the pressure stays the same.