Question

When 14.12 moles of mercury (ll) oxide decomposes, how many moles of oxygen gas will form ?

Answer 1

ANSWER

The number of moles of oxygen formed is 7.06 moles

EXPLANATION

Given that

The number of moles of mercury (II) oxide is 14.12 moles

Follow the steps below to find the number of moles of oxygen

Step 1; Write the balanced equation for the decomposition of the reaction

$\text{ 2HgO }\rightarrow\text{ 2Hg}_{(s)}\text{ + O}_{2(g)}$

In the reaction above, 2 moles HgO decompose to produce 2 moles Hg and 1 mole O2

Step 2; Find the number of moles of oxygen using a stoichiometry ratio

Let x represents the number of moles of oxygen

$\begin{gathered} \text{ 2 moles HgO }\rightarrow\text{ 1 mole O}_2 \\ \text{ 14.12 moles HgO}\rightarrow\text{ x mole O}_2 \\ \text{ cross multiply} \\ \text{ 2 moles HgO }\times\text{ x mole O}_2\text{ }=\text{ 1 mole O}_2\times\text{ 14.12 moles HgO} \\ \text{ Isolate x} \\ \text{ x = }\frac{1\text{ mole O}_2\times14.12moles\cancel{HgO}}{2moles\cancel{HgO}} \\ \text{ x = }\frac{14.12}{2} \\ \text{ x = 7.06 moles} \end{gathered}$

Therefore, the number of moles of oxygen formed is 7.06 moles