If 70.5 mol of an ideal gas is at 9.85 atm at 73.20 ∘ C, what is the volume of the gas?

Answer 1

Hi Ariel!

Since we have moles, pressure, and temperature for the gas, we can find the volume by using the Ideal Gas Law PV=nRT. In this equation, P is pressure in atm, V is volume in liters (L), n is moles, R is the gas constant 0.0821 L*atm/(mol*K) and T is the temperature in Kelvin. If we divide both sides of this equation by P, we get V=nRT/P. We're almost ready to plug everything in and get V, except that we need the temperature to be in Kelvin. To get Kelvin from our Celsius temperature, simply add 273 to it to get 346.20 K. Now plug in the values of n, R, T, and P:

V=(70.5 mol)(0.0821 L*atm/(mol*K))(346.20 K)/(9.85 atm)

If desired, we can drop the units; just remember that the answer will be in L:

V=(70.5)(0.0821)(346.20)/(9.85)=203 L to three significant figures.

I answered 203 L because my pressure and number of moles have the least number of significant figures (3) and we are doing a problem with multiplying and dividing; therefore my answer must have 3 significant figures too.

I hope that helps!