Question

How many grams of O₂ can be prepared from the thermal decomposition of 4.27 kg of HgO? Name and calculate the mass (in kg) of the other product.

Short answer

You need to calculate how many grams of O₂ can be prepared from the thermal decomposition of 4.27 kg of HgO. Also you need to write the name and calculate the mass (in kg) of the other product.

Step-by-step solution

Balanced equation

Thermal decomposition of HgO forms Hg and O₂. The balanced equation is

$\mathbf{2}\mathit{H}\mathit{g}\mathit{O}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\stackrel{\mathbf{\Delta }}{\mathbf{\to }}\mathbf{2}\mathit{H}\mathit{g}\mathbf{\left(}\mathbf{l}\mathbf{\right)}\mathbf{+}{\mathit{O}}_{\mathbf{2}}\mathbf{\left(}\mathbf{g}\mathbf{\right)}$

Calculation of moles of HgO 

According to the question,

Mass of HgO = 4.27kg = 4270g

Molecular mass of HgO = 216.6g/mol

Again you know,

$\mathit{m}\mathit{o}\mathit{l}\mathit{e}\mathit{s}\mathbf{=}\frac{\mathbf{m}\mathbf{a}\mathbf{s}\mathbf{s}\mathbf{\left(}\mathbf{g}\mathbf{i}\mathbf{v}\mathbf{e}\mathbf{n}\mathbf{\right)}}{\mathbf{m}\mathbf{a}\mathbf{s}\mathbf{s}\mathbf{\left(}\mathbf{m}\mathbf{o}\mathbf{l}\mathbf{a}\mathbf{r}\mathbf{\right)}}$

Moles of HgO

$\begin{array}{l}\mathbf{=}\frac{\mathbf{4270}}{\mathbf{216}\mathbf{.6}}\mathbf{\left(}\mathbf{m}\mathbf{o}\mathbf{l}\mathbf{\right)}\\ \mathbf{=}\mathbf{19}\mathbf{.7137}\mathbf{\left(}\mathbf{m}\mathbf{o}\mathbf{l}\mathbf{\right)}\end{array}$

Hence, moles of HgO are 19.7137mol.

Calculation of moles of O2

According to the balanced equation

$\mathbf{2}\mathit{H}\mathit{g}\mathit{O}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\stackrel{\mathbf{\Delta }}{\mathbf{\to }}\mathbf{2}\mathit{H}\mathit{g}\mathbf{\left(}\mathbf{l}\mathbf{\right)}\mathbf{+}{\mathit{O}}_{\mathbf{2}}\mathbf{\left(}\mathbf{g}\mathbf{\right)}$

2 moles of HgO produces 1 mole O₂

$\begin{array}{l}\mathbf{=}\mathbf{19}\mathbf{.7137}\mathbf{\times }\frac{\mathbf{1}}{\mathbf{2}}\mathbf{\left(}\mathbf{m}\mathbf{o}\mathbf{l}\mathbf{\right)}\\ \mathbf{=}\mathbf{9}\mathbf{.85685}\mathbf{\left(}\mathbf{m}\mathbf{o}\mathbf{l}\mathbf{\right)}\end{array}$

Now, moles of O₂

Hence, moles of O₂ are 9.85685mol.

Calculation of mass of O2

Again you know,

$\mathit{m}\mathit{a}\mathit{s}\mathit{s}\mathbf{=}\mathit{m}\mathit{o}\mathit{l}\mathit{e}\mathit{s}\mathbf{\times }\mathit{m}\mathit{a}\mathit{s}\mathit{s}\mathbf{\left(}\mathbf{m}\mathbf{o}\mathbf{l}\mathbf{a}\mathbf{r}\mathbf{\right)}$

Molar mass of O₂ is 32g/mol.

Now, mass of O₂

$\begin{array}{l}\mathbf{=}\mathbf{9}\mathbf{.85685}\mathbf{\times }\mathbf{32}\mathbf{\left(}\mathbf{g}\mathbf{\right)}\\ \mathbf{=}\mathbf{315}\mathbf{.4192}\mathbf{\left(}\mathbf{g}\mathbf{\right)}\end{array}$

Hence, 315.4192g of O₂ can be prepared from the thermal decomposition of 4.27 kg of HgO.

Calculation of moles of Hg

According to the balanced equation

$\mathbf{2}\mathit{H}\mathit{g}\mathit{O}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\stackrel{\mathbf{\Delta }}{\mathbf{\to }}\mathbf{2}\mathit{H}\mathit{g}\mathbf{\left(}\mathbf{l}\mathbf{\right)}\mathbf{+}{\mathit{O}}_{\mathbf{2}}\mathbf{\left(}\mathbf{g}\mathbf{\right)}$

2 moles of HgO produces 2 moles of Hg.

Now, moles of Hg

$\begin{array}{l}\mathbf{=}\mathbf{19}\mathbf{.7137}\mathbf{\times }\frac{\mathbf{2}}{\mathbf{2}}\mathbf{\left(}\mathbf{m}\mathbf{o}\mathbf{l}\mathbf{\right)}\\ \mathbf{=}\mathbf{19}\mathbf{.7137}\mathbf{\left(}\mathbf{m}\mathbf{o}\mathbf{l}\mathbf{\right)}\end{array}$

Hence, moles of Hg are 19.7137mol.

Calculation of mass of Hg 

Again you know,

$\mathit{m}\mathit{a}\mathit{s}\mathit{s}\mathbf{=}\mathit{m}\mathit{o}\mathit{l}\mathit{e}\mathit{s}\mathbf{\times }\mathit{m}\mathit{a}\mathit{s}\mathit{s}\mathbf{\left(}\mathbf{m}\mathbf{o}\mathbf{l}\mathbf{a}\mathbf{r}\mathbf{\right)}$

Molar mass of Hg is 200.6g/mol.

Now, mass of Hg

data-custom-editor="chemistry" $\begin{array}{l}\mathbf{=}\mathbf{19}\mathbf{.7137}\mathbf{\times }\mathbf{200}\mathbf{.6}\mathbf{\left(}\mathbf{g}\mathbf{\right)}\\ \mathbf{=}\mathbf{3954}\mathbf{.568}\mathbf{\left(}\mathbf{g}\mathbf{\right)}\\ \mathbf{=}\mathbf{3}\mathbf{.95}\mathbf{\left(}\mathbf{k}\mathbf{g}\mathbf{\right)}\end{array}$

Hence, the other product is Hg.

3.95kg of Hg can be prepared from the thermal decomposition of 4.27 kg of HgO.