Multiple choice

3 grams of $H_{2}$ and 24 grams of $O_{2}$ are present in a gaseous mixture at constant temperature and pressure. The partial pressure of $H_{2}$ is:

  1. $\dfrac{1}{3}$ of total pressure
  2. $\dfrac{2}{3}$ of total pressure
  3. $\dfrac{3}{2}$ of total pressure
  4. $\dfrac{1}{2}$ of total pressure
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Moles of H2 = 3/2 = 1.5. Moles of O2 = 24/32 = 0.75. Total moles = 2.25. Mole fraction of H2 = 1.5 / 2.25 = 2/3. Partial pressure = mole fraction * total pressure.

AI explanation

The partial pressure of a gas in a mixture is equal to its mole fraction. 3 grams of H2 is 1.5 moles and 24 grams of O2 is 0.75 moles, giving a total of 2.25 moles. The mole fraction of H2 is 1.5 divided by 2.25, which equals two thirds, meaning the partial pressure of H2 is two thirds of the total pressure.

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