Home >> Science & Nature >> Science

How to Find the Moles of a Product if Given the Moles of the Reactant

A mole is a unit of the amount of substance primarily used in chemistry. Moles are important in quantitative calculations because these units are directly proportional to the number of molecules that are involved in a chemical reaction. To compute the amount of the product, you need to know coefficients in the respective chemical reaction.

Instructions

- 1
  Write down the equation of the chemical reaction. For example, the oxidation of ethanol, or C2H5OH, occurs as follows:
  
  C2H5OH + 3O2 = 2CO2 + 3H2O.
  
  The numbers given before molecule formulas such as "3" or "2" are called reaction coefficients, and show how many corresponding molecules are involved in the reaction.
- 2
  Write down the equation coefficients at the reagent and the product of interest. In this example, the coefficient at ethanol is 1 while the coefficient at the product such as carbon dioxide (CO2) is 2.
- 3
  Divide the product coefficient by the coefficient at the reactant to determine the molar ratio. In this example, the ratio of carbon dioxide and ethanol is 2 / 1 = 2.
- 4
  Multiply the number of moles of the reactant by the molar ratio to calculate the number of moles of the product. For example, if the amount of ethanol is 3 moles, then the reaction results in formation of 6 moles (3 x 2) of carbon dioxide.

Science