MILLIMOLE CALCULATIONS

• When working with solutions, we often express the volume in milliliters (mL) rather than in liters.
• Likewise, we may express the amount of solute in millimoles ( mmol ) rather than in moles.
• Because mL is of a Liter and mmol is of a mole, molarity can also be expressed in mmol of solute in mL of solution:

• For problems that involve volume and concentration, solving in terms of millimoles and milliliters often involves more convenient numbers that using moles and Liters.
• It should also be noted that the reactions coefficients in a balanced chemical equation are exactly the same whether we express the amounts in moles or millimoles.
• When solving solution problems, the millimoles of solute can be easily obtained from given data as shown in the examples below.

Examples:

1. How many mmoles of solute are present in 125 mL of 0.100 M HCl solution?

2. If of 1.00 M HCl is added to of 0.80 M NaOH , what are the molarities of the solutes in the solution after all reaction has completed?