Question

A sample of pure solid naphthalene (C₁₀H₈) weighing 0.6410 g is burned completely with oxygen to (CO₂) and (H₂O) in a constant-volume calorimeter at 25°C. The amount of heat evolved is observed to be 25.79 kJ.

(a) Write and balance the chemical equation for the combustion reaction.

Short answer

Subpart (a)

$C_{10}{H}_8+12O_2\to 10C{O}_2+4H_{2}O$

Step-by-step solution

Given Information;

The weight of naphthalene is 0.6410 g.

The amount of heat evolved is 25.79 kJ.

Combustion reaction;

The fuel gets subjected to oxidation by combining with an oxidizing agent. This leads to energy liberation in the form of heat. This reaction is termed a combustion reaction.

The balanced chemical equation for the combustion reaction.Subpart (a)

Let us consider the reaction;

$C_{10}{H}_8+O_2\to C{O}_2+H_{2}O$

Here, the carbon atoms are not balanced. This can be balanced by placing a coefficient of 10 before CO₂on the right.

$C_{10}{H}_8+O_2\to 10C{O}_2+H_{2}O$

The hydrogen atoms are not balanced. This can be balanced by placing a coefficient of 4 before H₂O on the right. The resulting equation is:

$C_{10}{H}_8+O_2\to 10C{O}_2+4H_{2}O$

The oxygen atoms can be balanced by placing a coefficient of 12 before O₂as:

$C_{10}{H}_8+12O_2\to 10C{O}_2+4H_{2}O$

Therefore, the balanced chemical equation for the combustion reaction is:

$C_{10}{H}_8+12O_2\to 10C{O}_2+4H_{2}O$