What volume of gas (in mL) at STP would have 32.5 mL at 745.2 mm Hg and 23.5 degrees Celsius?

Question

What volume of gas (in mL) at STP would have 32.5 mL at 745.2 mm Hg and 23.5 degrees Celsius?

Answer 1

STP means a temperature of 273K and a pressure of 1 atm.

If you begin with 32.5 ml of gas at a temperature of 23.5ºC and a pressure of 745.2 mm Hg, we can then find what volume of gas that will occupy when you change the conditions to STP.

First, it is easiest if we change the mm Hg pressure to atm of pressure.

745.2 mm Hg x 1 atm/760 mm Hg = 0.981 atm

Temperature is always in K so converting 23.5 we get 23.5C + 273 = 296.5K

Then using the combined gas law P1V1/T1 = P2V2/T2 we can solve for V2 (volume at STP)

(0.981 atm)(32.5 ml)/296.5K = (1 atm)(V2)/273K

Solving for V2:

V2 = (0.981)(32.5)(273) / (296.5)(1)

V2 = 29.4 mls