Question

write the balanced chemical equation for each synthesis, decomposition, or combustion reaction
a) calcium hydrogen carbonate decomposes when heated
b) lithium mixes with nitrogen gas
c) hexane (c6h14) starts to combust

Explanation:

Step1: Write the un - balanced equation for part a

Calcium hydrogen carbonate (\(Ca(HCO_3)_2\)) decomposes when heated. The products are calcium carbonate (\(CaCO_3\)), carbon dioxide (\(CO_2\)) and water (\(H_2O\)).
\(Ca(HCO_3)_2(s)\xrightarrow{\Delta}CaCO_3(s)+CO_2(g)+H_2O(g)\)
This equation is already balanced.

Step2: Write the un - balanced equation for part b

Lithium (\(Li\)) reacts with nitrogen gas (\(N_2\)) to form lithium nitride (\(Li_3N\)).
\(Li(s)+N_2(g)
ightarrow Li_3N(s)\)
To balance the nitrogen atoms, we put a coefficient of \(2\) in front of \(Li_3N\) and \(3\) in front of \(N_2\). Then to balance the lithium atoms, we put a coefficient of \(6\) in front of \(Li\).
\(6Li(s)+N_2(g) = 2Li_3N(s)\)

Step3: Write the un - balanced equation for part c

Hexane (\(C_6H_{14}\)) combusts in the presence of oxygen (\(O_2\)) to form carbon dioxide (\(CO_2\)) and water (\(H_2O\)).
\(C_6H_{14}(l)+O_2(g)
ightarrow CO_2(g)+H_2O(g)\)
First, balance the carbon atoms: put a coefficient of \(6\) in front of \(CO_2\). Then balance the hydrogen atoms: put a coefficient of \(7\) in front of \(H_2O\). Now, for the oxygen atoms: the right - hand side has \(6\times2 + 7\times1=12 + 7 = 19\) oxygen atoms. So, we put a coefficient of \(\frac{19}{2}\) in front of \(O_2\). To get rid of the fraction, we multiply the entire equation by \(2\).
\(2C_6H_{14}(l)+19O_2(g)=12CO_2(g)+14H_2O(g)\)

Answer:

a) \(Ca(HCO_3)_2(s)\xrightarrow{\Delta}CaCO_3(s)+CO_2(g)+H_2O(g)\)
b) \(6Li(s)+N_2(g) = 2Li_3N(s)\)
c) \(2C_6H_{14}(l)+19O_2(g)=12CO_2(g)+14H_2O(g)\)