Question

Complete the missing components/variables given as x and y in the following reactions

(a) $Pb{(N{O}_3)}_2\left(aq\right)+2KI\left(aq\right)\to Pb{I}_2\left(x\right)+2KN{O}_3\left(y\right)$

(b) $Cu\left(s\right)+2AgN{O}_3\left(aq\right)\to Cu{(N{O}_3)}_2\left(aq\right)+x\left(s\right)$

(c) $Zn\left(s\right)+H_{2}S{O}_4\left(aq\right)\to ZnS{O}_4\left(x\right)+H_2\left(y\right)$

(d) $CaC{O}_3\left(s\right)\to xCaO\left(s\right)+C{O}_2\left(g\right)$

Answer 1

Understanding the reactions:

The reaction of Lead nitrate with Potassium Iodide:

• Lead Nitrate reacts with Potassium Iodide to form Lead Iodide and Potassium Nitrate.
• This is a double displacement reaction.
• The Lead Iodide is precipitated and Potassium Nitrate remains dissolved in the solution.
• $\underset{\mathrm{Lead}\mathrm{Nitrate}}{\mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{aq}\right)}+\underset{\mathrm{Potassium}\mathrm{Iodide}}{2\mathrm{KI}\left(\mathrm{aq}\right)}\to \underset{\mathrm{Lead}\mathrm{Iodide}}{{\mathrm{PbI}}_2\left(\mathrm{s}\right)}+\underset{\mathrm{Potassium}\mathrm{Nitrate}}{2{\mathrm{KNO}}_3\left(\mathrm{aq}\right)}$

The reaction of Copper and Silver Nitrate:

• Copper reacts with Silver Nitrate to form Copper Nitrate and Silver is precipitated.
• This is a redox reaction where Copper is oxidized and Silver is reduced due to their standard reduction potential.
• $\underset{\mathrm{Copper}}{\mathrm{Cu}\left(\mathrm{s}\right)}+\underset{\mathrm{Silver}\mathrm{Nitrate}}{2{\mathrm{AgNO}}_3\left(\mathrm{aq}\right)}\to \underset{\mathrm{Copper}\hspace{0.17em}\mathrm{Nitrate}}{\mathrm{Cu}{({\mathrm{NO}}_3)}_2\left(\mathrm{aq}\right)}+\underset{\mathrm{Silver}}{\mathrm{Ag}\left(\mathrm{s}\right)}$

The reaction of Zinc with dilute sulfuric acid: :

• Zinc reacts with dilute sulfuric acid to form zinc sulfate and hydrogen gas is released as a by-product.
• This reaction is an example of a displacement reaction.
• $\underset{\mathrm{Zinc}}{\mathrm{Zn}\left(\mathrm{s}\right)}+\underset{\mathrm{Sulfuric}\mathrm{Acid}}{{\mathrm{H}}_2{\mathrm{SO}}_4(\mathrm{aq}})\to \mathrm{Z}\underset{\mathrm{Zinc}\mathrm{Sulfate}}{{\mathrm{nSO}}_4\left(\mathrm{aq}\right)}+\underset{\mathrm{Hydrogen}}{{\mathrm{H}}_2\left(\mathrm{g}\right)}$

Decomposition of Calcium Carbonate:

• Decomposition of Calcium Carbonate leads to the formation of solid Calcium Oxide and Carbon Dioxide is released as a by-product.
• $\underset{\mathrm{Calcium}\mathrm{carbonate}}{{\mathrm{CaCO}}_3\left(\mathrm{s}\right)}\to \underset{\mathrm{Calcium}\mathrm{Oxide}}{\mathrm{CaO}\left(\mathrm{s}\right)}+\underset{\mathrm{Carbon}\mathrm{dioxide}}{{\mathrm{CO}}_2\left(\mathrm{g}\right)}$