Explain the reaction between zinc and copper sulfate, the reason for balancing chemical equations, and balance the given equations.

Here are the solutions to your questions:

1. When zinc reacts with copper sulphate solution, zinc displaces copper from the copper sulphate solution because zinc is more reactive than copper. This forms zinc sulphate and copper metal.

   $$\text{Zn(s)} + \text{CuSO}_4\text{(aq)} \rightarrow \text{ZnSO}_4\text{(aq)} + \text{Cu(s)}$$

   The blue color of copper sulphate solution fades, and a reddish-brown deposit of copper metal is formed on the zinc.

2. We balance a chemical equation to satisfy the Law of Conservation of Mass. This law states that matter cannot be created or destroyed in a chemical reaction, meaning the total mass of reactants must equal the total mass of products. Balancing ensures that the number of atoms of each element is the same on both sides of the equation.

3. Here are the balanced chemical equations:

   • a) $3\text{Fe(s)} + 4\text{H}_2\text{O(g)} \rightarrow \text{Fe}_3\text{O}_4\text{(s)} + 4\text{H}_2\text{(g)}$
   • b) $2\text{H}_2\text{(g)} + \text{O}_2\text{(g)} \rightarrow 2\text{H}_2\text{O(l)}$
   • c) $2\text{Pb(NO}_3)_2\text{(s)} \xrightarrow{\text{heat}} 2\text{PbO(s)} + 4\text{NO}_2\text{(g)} + \text{O}_2\text{(g)}$
   • d) $\text{N}_2\text{(g)} + 3\text{H}_2\text{(g)} \rightarrow 2\text{NH}_3\text{(g)}$
   • e) $\text{CH}_4\text{(g)} + 2\text{O}_2\text{(g)} \rightarrow \text{CO}_2\text{(g)} + 2\text{H}_2\text{O(g)}$

4. When steam passes over a red hot iron object, iron reacts with steam to form iron(II,III) oxide (magnetic iron oxide) and hydrogen gas.

   $$3\text{Fe(s)} + 4\text{H}_2\text{O(g)} \xrightarrow{\text{heat}} \text{Fe}_3\text{O}_4\text{(s)} + 4\text{H}_2\text{(g)}$$

5. Magnesium ribbon is rubbed with sandpaper before combustion to remove the protective layer of magnesium oxide ($\text{MgO}$) that forms on its surface. This oxide layer prevents the magnesium from reacting readily with oxygen, hindering its combustion.

6. The substance is Magnesium ($\text{Mg}$). It burns in air to produce magnesium oxide ($\text{MgO}$), which is a white ash. When magnesium oxide dissolves in water, it forms magnesium hydroxide ($\text{Mg(OH)}_2$), which is used as