At 40.0°C, the pressure inside a nitrogen-filled tennis ball with a volume of 148 cm3 is 235 kPa. How many moles of nitrogen (N2) are in the tennis ball?

To determine the number of moles of a gas, we need to have an expression that relates the pressure, temperature and volume of the system. For simplification, we assume that this gas is ideal so we use the equation PV=nRT. We calculate as follows:

PV=nRT

n = PV / RT

n = 235000 (1.48x10^-4) / (8.314) (40+273.15)

n = 0.01336 mol