Question

A gas is found to occupy a volume of 38.2 mL at 25.0ºC and an unknown

pressure. If this same gas occupies 37.5 mL at STP, determine what its unknown original pressure was in mm Hg.

Answer 1

836 mmHg

Step-by-step explanation:

Given data:

Initial volume = 38.2 mL

Initial temperature = 25°C (25+273=298 k)

Final volume = 37.5 mL

Final temperature = standard = 273 K

Final pressure = standard = 1 atm

Initial pressure = ?

Solution:

Formula:

P₁V₁/T₁ = P₂V₂/T₂

P₁ = Initial pressure

V₁ = Initial volume

T₁ = Initial temperature

P₂ = Final pressure

V₂ = Final volume

T₂ = Final temperature

Solution:

P₁ = P₂V₂T₁ /T₂ V₁

P₁ = 1 atm × 37.5 mL × 298 K / 273 K × 38.2 mL

P₁ = 11175 atm / 10428.6

P₁ = 1.1 atm

atm to mmHg

1.1 atm × 760 mmHg / 1 atm

836 mmHg