Make a thermochemical equation for the reaction of carbon combustion

Make a thermochemical equation for the reaction of carbon combustion if it is known that the combustion of 1.2 g of carbon releases 40.2 kJ of heat.

Given:
m (C) = 1.2 g
Q1 = 40.2 kJ

Find:
Thermochemical equation -?

Solution:
1) Using the periodic system of D.I.Mendeleev, calculate the molar mass of carbon:
M (C) = Mr (C) = Ar (C) = 12 g / mol;
2) Calculate the amount of carbon substance:
n (C) = m (C) / M (C) = 1.2 / 12 = 0.1 mol;
3) Make up the proportion and calculate the amount of heat:
0.1 mol C – 40.2 kJ;
1 mol C – Q kJ;
Q = 1 * 40.2 / 0.1 = 402 kJ;
4) Write the equation of the thermochemical reaction:
C + O2 => CO2 + 402 kJ.