Question

C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O

How many grams of carbon dioxide are produced when 390. kJ of energy are used in the following reaction?

Answer 1

Given:-

Energy = 390 kJ

Data that we need to know before solving this question:-

Molar mass of CO₂ = 44.01 g/mol

Enthalpy of combustion of C₂H₅OH = -1366.8 kJ/mol

NOte:- -ve sign denotes that the energy is released.

From the enthalpy of combustion of C₂H₅OH, we can say that-

1366.8 kJ of energy is released by the combustion of 1 mole of C₂H₅OH.

Therefore,

1 kJ of energy will be released by the combustion of (1/1366.8), i.e., 0.00073 moles of C₂H₅OH..

Hence,

390 kJ of energy will be released by the combustion of 0.00073*(390), i.e., 0.285 moles of C₂H₅OH..

No. of moles of C₂H₅OH combusted = 0.285 mol

Given combustion reaction:-

C₂H₅OH + 3O₂ -----> 2CO₂ + 3H₂O

From the stoichiometry of the combustion reaction, it is evident that 1 mole of C₂H₅OH reacts with 3 moles of O₂ to produce 2 moles of CO₂ and 3 moles of H₂O.

i.e.,

1 mole of C₂H₅OH produces 2 moles of CO₂.

Therefore,

0.285 moles of C₂H₅OH will produce 2*(0.285), i.e., 0.57 moles of CO₂.

Hence, no. of moles of CO₂ produced = 0.57 mol

We know that-

Mass (g) = [No. of moles (mol)]*[Molar mass (g/mol)] ------(a)

Therefore,

Mass of CO₂ produced = (0.57 mol)*(44.01 g/mol) -----using equation(a)

= (0.57)*(44.01) g

= 25.1 g

Hence, 25.1 grams of CO₂ will be produced under given conditions.