Question

An oxide of mercury will thermally decompose when heated. A 0.204 gram sample of the mercury oxide is decomposed to yield 0.189 grams of elemental mercury. What is the empirical formula of the mercury oxide

Answer 1

Answer:

$HgO$

Explanation:

Hello,

In this case, by knowing the mass of the oxide and the mass of the element mercury, one obtains its percentage as follows:

$\% Hg=\frac{0.189g}{0.204g}*100\%=92.6\%$

Consequently, oxygen's percentage is:

$\% O=100\%-92.6\%=7.4\%$

Now, the moles of each element for a 100-g sample:

$n_{Hg}=92.6gHg*\frac{1molHg}{200.59gHg} =0.462molHg\\n_{O}=7.4gO*\frac{1molO}{16gO}=0.462molO$

In such a way, the subscripts in the formula are given by:

$Hg=\frac{0.462mol}{0.462mol}=1\\ O=\frac{0.462mol}{0.462mol}=1$

Therefore, the empirical formula turns out:

$HgO$

Best regards.