Basically stoichiometry is the measurement of elements, that is, the study of chemical quantities consumed or produced in a chemical reaction. When we are performing it we are using a special chemical counting unit: the mole, a unit of measurement, and one mole of a substance contains 6.022 * 10^23 particles. Now mole ratio is defined as the ratio of moles of one substance to the moles of another substance in a balanced equation. If we are looking for the mole ratio between two substances, we need to look at the balanced equations for the coefficients in front of the substances you are interested in.
This should be your guiding mantra for doing stoichiometry problems!
