A sample of unknown pressure occupies 0.776L at a temperature of 298K. The sample of gas is then tested under known conditions and has a pressure of 32.6 kPa and occupies 0.664L at 303K. What was the original pressure of the gas?

A. 27.43 kPa

B. 38.62 kPa

C. 58.73 kPa

D. 84.11 kPa

27.43 kPa (Option A)

Explanation:

We can solve this by the use of the Ideal Gases Law.

P . V = n . R . T

As n and R are constant, we avoid them from the equation so:

P₁ . V₁ / T₁ = P₂ . V₂ / T₂

P₁ . 0776L / 298K = 32.6 kPa . 0.664L / 303K

P₁ . 0776L / 298K = 0.0714 kPa .L/K

P₁ . 0776L = 0.0714 kPa .L/K  . 298K

P₁ = 21.289 kPa.L / 0.776L

P₁ = 27.43 kPa