Question

chemistry 20
final exam 2025
name: ebteasam
gases
use the following information to answer the next question.
a sample of helium gas occupies 465 ml at 400 kpa. more pressure is applied from
the surroundings and the final pressure becomes 4.94 atm, but the temperature
remains unchanged.

1. the final volume occupied by the gas will be

□ 320 ml
□ 421 ml
□ 372 ml
□ 475 ml

Explanation:

Step1: Convert pressure units

We know that \(1\space atm = 101.325\space kPa\). So, \(P_2=4.9\space atm\times101.325\space kPa/atm = 496.4925\space kPa\), \(P_1 = 400\space kPa\), \(V_1=465\space mL\).

Step2: Apply Boyle's Law

Boyle's Law is \(P_1V_1=P_2V_2\) (since \(T\) is constant). Then \(V_2=\frac{P_1V_1}{P_2}\).
Substitute the values: \(V_2=\frac{400\space kPa\times465\space mL}{496.4925\space kPa}\)
\(V_2=\frac{186000}{496.4925}\space mL\approx 375\space mL\approx372\space mL\) (approximate due to rounding in pressure - unit conversion)

Answer:

\(372\space mL\)