Question

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

Write and balance the chemical equation for the combustion reaction.

Answer 1

Answer: C10H8 + 12O2 ----> 10CO2 + 4H2O

Step-by-step explanation:

To balance this, we have to make sure that the same number of atoms exist at both sides (Conservation of energy)

Note:The reaction is exothermic, giving off heat energy.

Left hand side: C= 10,

H=8,

O= 2×12=24

Right hand side: C= 10×1=10,

H= 4×2=8,

O=10×2=20 (for 10CO2) and 4×1=4 (All equal to 24)

With the above analysis, it is clear that numbers had to be added to molecules to get an equal number of atoms for both sides.