How are mole ratios used in chemical calculations?

Question

Cameron Andrews · Accepted Answer

In order to determine the mole ratio, we need to begin with a balanced chemical equation.

For this reaction the balanced chemical equation is
#N_2 + 3H_2 -> 2NH_3#

The mole ratios are determined using the coefficients of the substances in the balanced chemical equation.

#1 mol n_2 : 3 mol H_2 : 2 mol NH_3#

The mole ratios for each substance pair would be

#1 mol N_2 : 3 mol H_2#

#(1 mol N_2)/ (3 mol H_2)# or #(3 mol H_2)/ (1 mol N_2)#

#1 mol N_2 : 2 mol NH_3#

#(1 mol N_2)/ (2 mol NH_3)# or #(2 mol NH_3)/ (1 mol N_2)#

#3 mol H_2 : 2 mol NH_3#

#(3 mol H_2)/ (2 mol NH_3)# or #(2 mol NH_3)/ (3 mol H_2)#

Mole ratios are used as a means of comparison of substances in a balanced chemical equation in order to determine amounts.

Using the same reaction for ammonia
#N_2 + 3H_2 -> 2NH_3#

How many moles of Hydrogen gas are necessary to react with 5 moles of Nitrogen.

We can use conversion factors in a process called stoichiometry.

# 5 mol N_2 x (3 mol H_2)/(1 mol N_2) = 15 mol H_2#

Mole ratio provides a comparison to cancel units. In this case the moles of Nitrogen cancel and we determine the moles of Hydrogen.

I hope this was helpful.
SMARTERTEACHER

Jeremiah Adams · Answer

undefined Mole ratios are used in chemical calculations to convert between the amounts of reactants and products in a chemical reaction. They are derived from the balanced chemical equation and represent the ratio of moles of one substance to another in the reaction. Mole ratios allow us to determine the amounts of reactants consumed or products formed in a reaction and are essential for stoichiometry calculations.