In this lab, you generated hydrogen gas by reacting magnesium metal with hydroch

Question

In this lab, you generated hydrogen gas by reacting magnesium metal with hydrochloric acid. The following question has you apply the same calculations you used to a different chemical reaction.

Mercuric oxide (HgO (s)) decomposes according to the following balanced chemical reaction:

2 HgO (s) + heat --> 2 Hg (l) + O2 (g)

A 2.154 gram sample of HgO produces 125.0 mL of oxygen gas collected over water at 24.00 °C and at an atmospheric pressure of 763.0 mmHg. Calculate the molar volume for oxygen gas at STP in units of L/mol. Also calculate the % ERROR (theoretical molar volume of a gas at STP is 22.4 L/mol). Show all calculations on an attached sheet; also include correct units and significant figures.

Explanation / Answer

2 HgO (s) + heat --> 2 Hg (l) + O2 (g)

2 moles of HgO on decomposes to gives 1 moles of O2

2*216.6g of HgO on decomposes to gives 22.4 L of O2

2.154g of HgO on decomposes to gives = 22.4*2.154/2*216.6   = 0.1114 L of O2 = 111.4ml

% ERROR    = (125-111.4)*100/111.4   = 12.21%

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