Dilution is a common type of problems given to students in the concentration chapter of their chemistry class. To dilute something means to add water to the solution, which will in turn decrease the concentration.

The formula for dilution is M1V1= M2V2

where M1= Molarity 1

V1 = Volume 1

M2 = Final Molarity

V2= Final Volume

Note, that for this formula your volume can be in any units as long as it is consistent on both sides.

When do we use this formula and how do we know that our question is a dilution question?

1. If the question itself mention the word dilute, you can use the formula. For example 20 ml of 5M solution were diluted to 59ml, what is the new Molarity?

2. If you see that in the question, water is added. For example, what was the initial concentration of 20ml of solution if 60 ml of water was added to create 4M solution?

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