What amount of heat will be released during the combustion of 15.5 g of phosphorus?

What amount of heat will be released during the combustion of 15.5 g of phosphorus? The thermochemical equation of the reaction is 4P + 5O2 = 2P05 + 3010kJ.

Given:
m (P) = 15.5 g
Q Art. = 3010 kJ

To find:
Q1 -?

Solution:
1) Write the equation of the thermochemical reaction:
4P + 5O2 => 2P2O5 + 3010 kJ;
2) Calculate the molar mass P:
M (P) = Mr (P) = Ar (P) = 31 g / mol;
3) Calculate the amount of substance P:
n (P) = m (P) / M (P) = 15.5 / 31 = 0.5 mol;
4) Calculate the amount of released heat, making up and solving the proportion:
4 mol P – 3010 kJ of heat;
0.5 mol P – (x) kJ of heat;
x = 0.5 * 3010/4 = 376.25;
Q1 = x = 376.25 kJ.

Answer: The amount of released heat is 376.25 kJ.