1.55 L of a gas is collected at 25.0°C and 720.0 mm Hg. What is the volume at STP?

[cynthu m]

1.55 L of a gas is collected at 25.0°C and 720.0 mm Hg. What is the volume at STP?

[Leslie C]

So the ideal gas law is:P1V1/T1 = P2V2/T2 right?STP is: V = ? L, T = 273, P = 760 torrSO, 25 C = 25 + 273 = 298 Kelvin(720)(1.55) / (298 K) = (760) P2 / (273 K)P2 = 1.35 mm Hg

[Farzin]

The mathematical form of the Combined Gas Law is:P1 x V1 / T1 = P2 x V2 / T2When any five of the six quantities in the equation are known, the sixth can be calculated. Unit Conversions:P1 = 720.mmHg / 760 mmHg x 1.000 atm = 0.947 atmT1 = 25C + 273.15 = 298 °KFinal Calculations:V2 = P1V1T2/P2T1= 0.947 atm x 1.55 L x 2.73x102 °K / (1. atm x 298 °K) = 1. L