To calculate for the pressure of the system, we need an equation that would relate the
number of moles (n), pressure (P), and temperature (T) with volume (V). There are a number of equations that would relate these values however most are very complex equations. For
simplification, we assume the gas is an ideal gas. So, we use PV = nRT.
PV = nRT where R is the universal gas
constant
P = nRT / V
P = 3.40 mol ( 0.08205 L-atm / mol-K ) (251 + 273.15 K) / 1.75 L
P = 83.56 atm
Therefore, the pressure of the gas at the given conditions of volume and temperature would be 83.56.