Question

Balance the following equations and indicate whether they are combination, decomposition, or combustion reactions: (a) ${\mathrm{C}}_3{\mathrm{H}}_6(g)+{\mathrm{O}}_2(g)⟶{\mathrm{CO}}_2(g)+{\mathrm{H}}_2\mathrm{O}(g)$ (b) ${\mathrm{NH}}_4{\mathrm{NO}}_3(s)⟶{\mathrm{N}}_2\mathrm{O}(g)+{\mathrm{H}}_2\mathrm{O}(g)$ (c) ${\mathrm{C}}_5{\mathrm{H}}_6\mathrm{O}(l)+{\mathrm{O}}_2(g)⟶{\mathrm{CO}}_2(g)+{\mathrm{H}}_2\mathrm{O}(g)$ (d) ${\mathrm{N}}_2(g)+{\mathrm{H}}_2(g)⟶{\mathrm{NH}}_3(g)$ (e) ${\mathrm{K}}_2\mathrm{O}(s)+{\mathrm{H}}_2\mathrm{O}(l)⟶\mathrm{KOH}(aq)$

Short answer

(a) $C_3{H}_6(g)+\frac{9}{2}{O}_2(g)⟶3C{O}_2(g)+3H_{2}O(g)$ - Combustion reaction (b) $N{H}_{4}N{O}_3(s)⟶N_{2}O(g)+2H_{2}O(g)$ - Decomposition reaction (c) $C_5{H}_{6}O(l)+\frac{15}{2}{O}_2(g)⟶5C{O}_2(g)+3H_{2}O(g)$ - Combustion reaction (d) $N_2(g)+3H_2(g)⟶2N{H}_3(g)$ - Combination reaction (e) $K_{2}O(s)+H_{2}O(l)⟶2KOH(aq)$ - Combination reaction

Step-by-step solution

(a) Balancing the equation

First, we balance the number of atoms for each element on both sides of the equation. This involves adding coefficients in front of the chemical compounds: $C_3{H}_6(g)+\frac{9}{2}{O}_2(g)⟶3C{O}_2(g)+3H_{2}O(g)$ The balanced equation is now: $C_3{H}_6(g)+\frac{9}{2}{O}_2(g)⟶3C{O}_2(g)+3H_{2}O(g)$ This is a combustion reaction, as it involves a hydrocarbon reacting with oxygen to produce carbon dioxide and water.

(b) Balancing the equation

Balancing the atoms for each element on both sides of the equation: $N{H}_{4}N{O}_3(s)⟶N_{2}O(g)+2H_{2}O(g)$ The balanced equation is now: $N{H}_{4}N{O}_3(s)⟶N_{2}O(g)+2H_{2}O(g)$ This is a decomposition reaction, as a single compound breaks down into two or more simpler compounds.

(c) Balancing the equation

Balancing the atoms for each element on both sides of the equation: $C_5{H}_{6}O(l)+\frac{15}{2}{O}_2(g)⟶5C{O}_2(g)+3H_{2}O(g)$ The balanced equation is now: $C_5{H}_{6}O(l)+\frac{15}{2}{O}_2(g)⟶5C{O}_2(g)+3H_{2}O(g)$ This is a combustion reaction, as it involves a hydrocarbon reacting with oxygen to produce carbon dioxide and water.

(d) Balancing the equation

Balancing the atoms for each element on both sides of the equation: $N_2(g)+3H_2(g)⟶2N{H}_3(g)$ The balanced equation is now: $N_2(g)+3H_2(g)⟶2N{H}_3(g)$ This is a combination reaction, as simpler molecules (nitrogen and hydrogen) combine to form a more complex molecule (ammonia).

(e) Balancing the equation

Balancing the atoms for each element on both sides of the equation: $K_{2}O(s)+H_{2}O(l)⟶2KOH(aq)$ The balanced equation is now: $K_{2}O(s)+H_{2}O(l)⟶2KOH(aq)$ This is a combination reaction, as simpler molecules (potassium oxide and water) combine to form a more complex molecule (potassium hydroxide).