A ball has a volume of 9.0 liters and is subjected to a pressure of 3.5 atmospheres when its temperature is 74 °C. According to the ideal gas law, how many moles of gas are in the ball?

To determine the number of moles of the gas, we need to relate moles to pressure, temperature and volume. To simplify things, we assume the gas is ideal so we use the ideal gas equation PV=nRT.

PV = nRT

n = PV / RT

n = 3.5 (9.0) / 0.08205 (74+273.15)

n = 1.1059 mol