Question

Give the balanced equation for

(i) A direct combination reaction involving two elements, one of which is a non-metal

(ii) A thermal decomposition reaction involving heat on limestone(calcium carbonate

(iii) An electrolytic decomposition reaction involving neutral liquid

(iv) A displacement reaction involving a metal above hydrogen in the activity series with copper(II) sulphate solution

(v) A double decomposition neutralization reaction involving acid and base

(vi) A white precipitate was obtained during a double decomposition reaction involving a silver salt with sodium salt.

Answer 1

(i) A direct combination reaction involving two elements, one of which is a non-metal

A combination reaction between calcium and oxygen (non-metal) to form calcium oxide.

$2\mathrm{Ca}\left(\mathrm{s}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2\mathrm{CaO}\left(\mathrm{s}\right)$

(ii) A thermal decomposition reaction involving heat on limestone(calcium carbonate)

When limestone is heated, it decomposes into calcium oxide and carbon dioxide.

${\mathrm{CaCO}}_3\left(\mathrm{s}\right)\stackrel{∆}{\to }\mathrm{CaO}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)$

(iii) An electrolytic decomposition reaction involving neutral liquid

When electricity is passed through acidified water, it decomposes into hydrogen and oxygen.

$2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{aq}\right)\stackrel{\mathrm{Electricity}}{\to }2{\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)$

(iv) A displacement reaction involving a metal above hydrogen in the activity series with copper(II) sulphate solution

When zinc reacts with copper sulphate, zinc being highly reactive displaces copper which is less reactive.

$\mathrm{Zn}\left(\mathrm{s}\right)+{\mathrm{CuSO}}_4\left(aq\right)\to \mathrm{Cu}\left(\mathrm{s}\right)+{\mathrm{ZnSO}}_4\left(aq\right)$

(v) A double decomposition neutralization reaction involving acid and base

When an acid and base react, it forms salt and water.

$\mathrm{NaOH}\left(aq\right)+\mathrm{HCl}\left(aq\right)\to \mathrm{NaCl}\left(aq\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

(vi) A white precipitate was obtained during a double decomposition reaction involving a silver salt with sodium salt

A double decomposition reaction is a type of decomposition reaction in which two constituent reactants interchange positive and negative ions and form two new compounds.

${\mathrm{AgNO}}_3\left(aq\right)+\mathrm{NaCl}\left(aq\right)\to \mathrm{AgCl}\left(\mathrm{s}\right)+{\mathrm{NaNO}}_3\left(aq\right)$