Question

`60` `mL` of a `1.5` `M` solution of `HCl` is diluted to a volume of `2.0` `L`. What is the concentration of the new solution?

Answer 1

Step 1: `n = CV = 1.5xx0.060 = 0.09` `mol`

Step 2:
`C = n/V = 0.09/2 = 0.045` `molL^-1`

Explanation:

The solution to this is a two-step process: finding the number of moles of HCl in the initial solution, then calculating the concentration of the final solution.

We will use the equation `C = n/V` in both steps.

`C` is the concentration in `molL^-1` (also called `M`), `n` is the number of moles of solute and `V` is the volume of the solution in `L`.

For step 1, rearrange to make `n` the subject:

`n = CV = 1.5xx0.060 = 0.09` `mol` (changing the volume from `mL` to `L`)

For step 2, the original formula is what we need:

`C = n/V = 0.09/2 = 0.045` `molL^-1`