Answer to Question #122379 in Chemistry for aljoc

Question

Oxygen gas generated by the decomposition of mercury(II) oxide is collected by the displacement of water. Given that the atmospheric pressure is 100.34 kPa and the water temperature is 24.0°C, predict the pressure of the oxygen.

Answer 1

Solution:

Mercury(II) oxide decomposes when heated to produce mercury and oxygen gas.

2HgO(s) → 2Hg(l) + O₂(g)

The partial pressure of oxygen can be calculated using Dalton's Law of Partial Pressures, which tells us that the total pressure of a gaseous mixture is equal to the sum of the partial pressure of each gas that's a part of that mixture.

Mathematically, we can write this as

P_total=∑P_i

In our case, the total pressure of the mixture will be equal to the partial pressure of water and the partial pressure of oxygen gas

P_total = P_water + P_O2

The vapor pressure of water at 24.0°C is approximately 2.975 kPa (https://www.endmemo.com/chem/vaporpressurewater.php)

Thus:

P_O2 = P_total - P_water

P_O2 = 100.34 kPa - 2.975 kPa = 97.365 kPa

P_O2 = 97.365 kPa

Answer: P_O2 = 97.365 kPa