Question

If $2.0moles$ of propane are burned (reacted with oxygen), how many moles of carbon dioxide will be produced?
${C_3}{H_8}(g) + 5{O_2}(g) \to 3C{O_2}(g) + 4{H_2}O(g)$

Answer 1

As we know propane is a fuel which is used in many outdoor grills, that burns in oxygen to produce carbon dioxide gas and also water vapor. In order to solve this question, we can use the concept of stoichiometry. Stoichiometry can be defined as a branch of chemistry that involves using the relationships between reactants or products in a chemical reaction to obtain the desired quantitative data.

Complete step-by-step answer: As we know the reaction is given by,
${C_3}{H_8}(g) + 5{O_2}(g) \to 3C{O_2}(g) + 4{H_2}O(g)$
From this we can deduce the mole ratio between propane and carbon dioxide.
By mole ratio it means a conversion factor that relates the amount of a substance in moles, which in this case is $1:3$ because from the equation we get that one mole of propane gives three moles of carbon dioxide.
Hence, equation to find out moles of carbon dioxide produced from two moles of propane is given by,
$2moles{C_3}{H_8} \times \dfrac{{3molesC{O_2}}}{{1mole{C_3}{H_8}}} = 6moles$
Hence we can say that $6moles$ of carbon dioxide is produced from two moles of propane.

Additional information: The most common type of stoichiometric relationship is the mole ratio, which can relate to the amounts in moles of any two substances in a chemical reaction. We can write a mole ratio for a pair of substances by looking at the coefficients in front of each element or compound in the balanced chemical equation.

Note: Stoichiometry is based on the law of conservation of mass where the total mass of the reactants is equal to the total mass of the products, which means that the relations among the quantities of reactants and the products form a ratio of positive integers. Hence, we can say that, if the amounts of the separate reactants are known, then the amount of the product can be calculated.