1.) Why must the oxidation of copper with HNO₃ be carried out in a fume hood?

1)

The mentioned reaction of copper with nitric acid is as follows:

{eq}{\rm{Cu}} + {\rm{HN}}{{\rm{O}}_{\rm{3}}} \to {\rm{Cu}}{\left( {{\rm{N}}{{\rm{O}}_{\rm{3}}}} \right)_2} + {\rm{N}}{{\rm{O}}_{\rm{2}}} + {{\rm{H}}_{\rm{2}}}{\rm{O}} {/eq}

In this reaction, when Cu is heated with nitric acid, {eq}{\rm{N}}{{\rm{O}}_{\rm{2}}} {/eq} evolves. This is toxic gas and damages the lungs when breathed in. It also irritates the skin and can cause mutations.

If a fume hood is used when the reaction is taken place, the exposure of toxic emission of {eq}{\rm{N}}{{\rm{O}}_{\rm{2}}} {/eq} will not happen. The gas will be blown up with the help of the fan and it will be released outside after filtration.

Therefore, it is always told to do "oxidation of copper with nitric acid inside a fume hood".

2)

Decant:

Decanting in a reaction is separating the solid phase form a liquid after the sedimentation.

Filtrate:

Filtrate is the final product that is obtained after filtration. It is the part of solution left after filtration.

Supernate:

Supernate is the liquid above the solid that has settled down in the solution.

Liquid:

Liquids are a type of matter that can flow. The intermolecular attraction will be slightly less in liquids.

3)

In CuO, {eq}{\rm{C}}{{\rm{u}}^{{\rm{2 + }}}} {/eq} is the cation with +2 oxidation state and {eq}{{\rm{O}}^{{\rm{2}} - }} {/eq} is the anion with -2 oxidation state. Thus, the name of the compound is copper {eq}\left( {{\rm{II}}} \right) {/eq} oxide.

In {eq}{\rm{Cu}}{\left( {{\rm{N}}{{\rm{O}}_{\rm{3}}}} \right)_{\rm{2}}} {/eq} {eq}{\rm{C}}{{\rm{u}}^{{\rm{2 + }}}} {/eq} is the cation with +2 oxidation state and the oxidation state of {eq}{\rm{N}}{{\rm{O}}_{\rm{3}}}^ - {/eq} anion is -1. Therefore, the compound is copper {eq}\left( {{\rm{II}}} \right) {/eq} nitrate.

In, {eq}{\rm{Cu}}{\left( {{\rm{OH}}} \right)_2} {/eq} {eq}{\rm{C}}{{\rm{u}}^{{\rm{2 + }}}} {/eq} s the cation with +2 oxidation state and the oxidation state of {eq}{\rm{O}}{{\rm{H}}^ - } {/eq} is -1. Therefore, the name of the compound is copper {eq}\left( {{\rm{II}}} \right) {/eq} hydroxide.

In, {eq}{\rm{CuS}}{{\rm{O}}_4} {/eq} {eq}{\rm{CuS}}{{\rm{O}}_4} {/eq} is the cation with +2 oxidation state and {eq}{\rm{S}}{{\rm{O}}_{\rm{4}}}^{2 - } {/eq} sulfate is the anion with -2 oxidation state. The name of the compound is copper sulfate.

In HCl, the cation {eq}{{\rm{H}}^ + } {/eq} is with +1 oxidation state and {eq}{\rm{C}}{{\rm{l}}^ - } {/eq} is the anion with -1 oxidation state.Therefore, the IUPAC name is hydrogen chloride. It is commonly known as hydrochloric acid.

In {eq}{{\rm{H}}_2}{\rm{S}}{{\rm{O}}_4} {/eq} there are two hydrogen, {eq}{{\rm{H}}^ + } {/eq} with +1 oxidation state and that of the anion which is {eq}{\rm{S}}{{\rm{O}}_{\rm{4}}}^{2 - } {/eq} is -2. The name of the compound is sulphuric acid.

4.

Given data:

• The obtained mass is {eq}0.445\;{\rm{g}} {/eq}.

• The initial mass is {eq}0.577\;{\rm{g}} {/eq}.

The percentage recovery can be calculated as follows

{eq}\begin{align*} {\rm{Percentage}}\;{\rm{recovery}} &= \left( {\dfrac{{{\rm{Obtained}}\;{\rm{mass}}}}{{{\rm{Initial}}\;{\rm{mass}}}}} \right) \times 100\\ &= \left( {\dfrac{{0.445\;{\rm{g}}}}{{0.577\;{\rm{g}}}}} \right) \times 100\\ &= 77.1\;\% \end{align*} {/eq}

Therefore, the obtained mass is {eq}77.1\;\% {/eq}

5.

The reaction mentioned above is the heating of copper hydroxide for the formation of copper oxide and water.

The chemical equation for the reaction is as follows:

{eq}{\rm{Cu}}{\left( {{\rm{OH}}} \right)_2} \overset{\Delta}{\rightarrow} {\rm{CuO}} + {{\rm{H}}_{\rm{2}}}{\rm{O}} {/eq}