Type of Stoichiometry

*Mole-to-Mole Problems

                If the number of one of the substance is given in the problem, you can determine the number of moles of any of the other substances in the reaction by using a mole conversion factor based on the coefficients in the balanced equation.

 

                                                Mole A                     Mole  B

Sample problem:

                

                Consider the reaction between ammonia and oxygen to form nitrogen and water.

 

                                      4NH3 + 3O2                   2N2 + 6H2O

                How many moles of O2 are needed to react with 8 moles of NH3?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Source: Phoenix Science Series-Chemistry.

 

 

Mole-to-Gram Problems

                The Gram is the most convenient unit for measuring quantities of reactants or products in the laboratory. In order to to convert moles to grams or grams to moles, you have to make use of the given compound.

Sample problem:

                Nitrogen gas reacts with Hydrogen gas to produce ammonia, as shown in the following equation:

                                      N2(g)   +3H2(g)                     2NH3

                How many grams of H2 are needed to react with 2.5 moles of N2 ?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Source: Phoenix Science Series-Chemistry.

 

 

written by: Nina Manuel