Gas Law Chemistry

Question

Use Boyle's, Charles's, or Gay-Lussac's law to calculate the missing value in each of the following.

(a) V₁ = 2.0 L, P₁ = 0.79 atm, V₂ = 1.0 L, P₂ = ?

 atm

(b) V₁ = 270 mL, T₁ = ?, V₂ = 400. mL, T₂ = 298 K

 K

(c) V₁ = 0.55 L, P₁ = 740 mm Hg, V₂ = 0.81 L, P₂ = ?

 mm Hg

Answer 1

For a, we would use Boyle's law where temperature is held constant and the amount of gas does not change:

P₁V₁ = P₂V₂

0.79 atm(2.0 L) = P₂(1.0L)

0.79 atm(2.0 L) ₌ 1.58 atm

1.0 L

For b, we will be using Charles's Law:

V₁/T₁ = V₂/T₂ Use algebra to rearrange the equation to get T₁ by itself.

V₁(T₂) = T₁

V₂

270 mL(298 K) ₌ 201 K

400 mL

For c, we will be again be using Boyle's law:

P₁V₁ = P₂V₂

P₁V_{1 =} P₂

V₂

740 mm Hg(0.55 L) ₌ 502 mmHg

0.81 L