# How do you do dilution calculations?

##### 1 Answer

You use the formula

In any dilution, the number of moles of solute stays the same. You are simply increasing the amount of solvent in the solution.

You know that

Moles =

So, if moles before dilution = moles after dilution,

**Example 1.** Calculating new concentration

A chemist starts with 50.0 mL of a 0.400 mol/L NaCl solution and dilutes it to 1000. mL. What is the concentration of NaCl in the new solution?

**Solution 1**

Note: You don't have to convert the volumes to litres, but you must use the same units on each side of the equation.

**Example 2**. Calculating initial volume

A chemist wants to make 500. mL of 0.0500 mol/L HCl by diluting a 6.00 mol/L HCl solution. How much of that solution should she use?

**Solution 2**

Hope this helps.