Question

A ballon is inflated with 2.42L of helium at a temperature of 27.0°C. When put in the freezer, the volume changes to 2.37L and -8.8°C, and the pressure is measured to be 754torr. What was the initial pressure?

Answer 1

Answer:

838 torr  

Step-by-step explanation:

To solve this problem, we can use the Combined Gas Laws:

p₁V₁/T₁ = p₂V₂/T₂            Multiply each side by T₁

   p₁V₁ = p₂V₂ × T₁/T₂     Divide each side by V₁

      p₁ = p₂ × V₂/V₁ × T₁/T₂

Data:

p₁ = ?;             V₁ = 2.42 L; T₁ =  27.0 °C

p₂ = 754 torr; V₂ = 2.37 L; T₂ =  -8.8 °C

Calculations:

(a) Convert temperatures to kelvins

T₁ = (27.0 + 273.15) K = 300.15 K

T₂ = (-8.8 + 273.15) K = 264.35 K

(b) Calculate the pressure

p₁ = 754 torr × (2.37 L/2.42) × (300.15/264.35)  

p₁ = 754 torr × 0.979 × 1.135

p₁ = 838 torr