Question

How are mole ratios used in chemical calculations?

Answer 1

Mole ratios are the conversion factors which use the moles of the given substance to find the moles of the unknown substance involved in a chemical reaction. Now you can easily answer the given substance.

Complete answer:
First of all let’s discuss what the mole is. Mole is that which tells us about the amount or the quantity of the substance. It can be in terms of either atoms , molecules , particles or grams, liters etc.
Now coming next to the mole ratio. Mole ratio is a conversion factor (i.e. the formula which is applied to change one set of units to another i.e., it is formula) which relates i.e. compares the quantities or the amount of the any two substances which are involved in a chemical reaction.
Now consider the chemical reaction of the formation of the ammonia in which one mole of nitrogen reacts with the three mole of hydrogen and results in the formation of the two moles of ammonia.
The reaction occurs as:
${{N}_{2}}+3{{H}_{2}}\to 2N{{H}_{3}}$
Now, the mole ratio of the this reaction can be calculated as;
$\begin{aligned} & \dfrac{1\text{ mole of }{{\text{N}}_{2}}}{2\text{ moles of N}{{\text{H}}_{3}}}\text{ or }\dfrac{2\text{ moles of N}{{\text{H}}_{3}}}{1\text{ mole of }{{\text{N}}_{2}}} \\\ & \dfrac{1\text{ mole of }{{\text{N}}_{2}}}{\text{3 moles of }{{\text{H}}_{2}}}\text{ or }\dfrac{\text{3 moles of }{{\text{H}}_{2}}}{1\text{ mole of }{{\text{N}}_{2}}} \\\ & \dfrac{\text{3 moles of N}{{\text{H}}_{3}}}{2\text{ moles of N}{{\text{H}}_{3}}}\text{ or }\dfrac{2\text{ moles of N}{{\text{H}}_{3}}}{\text{3 moles of N}{{\text{H}}_{3}}} \\\ \end{aligned}$
Thus, in this way, we can use the mole ratios in chemical calculations.

Note:
While we are solving the mole ratio problem, then the substance which is given is written first in terms of mole and then, after that suitable conversion factor is selected in order to convert from moles of the given substance to moles of the unknown substance which has to be found.