How do you determine moles from a balanced equation?

You determine moles from a balanced equation by using the stoichiometric coefficients in front of the reactants and products.

In a balanced chemical equation, the numbers in front of the chemical formulas (stoichiometric coefficients) represent the number of moles of each substance involved in the reaction. These coefficients establish the ratio of reactants to products in the reaction. For example, in the equation 2H2 + O2 → 2H2O, the coefficients tell us that two moles of hydrogen react with one mole of oxygen to produce two moles of water.

To determine the number of moles from a balanced equation, you need to know the amount of at least one substance involved in the reaction. This could be the number of moles of a reactant or product, or the mass of a reactant or product (from which you can calculate the number of moles using the molar mass). Once you know the number of moles of one substance, you can use the stoichiometric coefficients to calculate the number of moles of any other substance in the reaction.

For instance, if you know that you have 4 moles of hydrogen in the above reaction, you can use the stoichiometric coefficients to determine that you need 2 moles of oxygen (since the ratio of hydrogen to oxygen is 2:1) and will produce 4 moles of water (since the ratio of hydrogen to water is 2:2, or 1:1).

Remember, the key to determining moles from a balanced equation is understanding the stoichiometric coefficients and how they represent the mole ratios of the reactants and products.