Question

A helium balloon is filled on the ground where the atmospheric pressure is 768 torr. The volume of the balloon is 8.00 m3. When the balloon reaches an altitude of 4200 m, its volume is found to be 16.8 m3. Assuming that the temperature remains constant, what is the air pressure at 4200 m in torr? A. 1.61 x 103 B. 366 C. 543 D. 111 E. 89

Answer 1

Answer:

The correct option is: B. 366 torr

Explanation:

Given: On the ground- Initial Volume: V₁ = 8.00 m³, Initial Atmospheric Pressure: P₁= 768 torr;

At 4200 m height- Final Volume: V₂ = 16.80 m³, Final Atmospheric Pressure: P₂ = ?

Amount of gas: n, and Temperature: T = constant

According to the Boyle's Law, for a given amount of gas at constant temperature:         P₁ V₁ = P₂ V₂

⇒  P₂ = P₁ V₁ ÷ V₂

⇒  P₂ = [(768 torr) × (8.00 m³)] ÷ (16.80 m³)

⇒  P₂ = 365.71 torr ≈ 366 torr

Therefore, the final air pressure at 4200 m height: P₂ = 366 torr.