Question

If 450 mL of 6.0 M KBr solution is diluted to 900 mL, what is the concentration of the KBr solution?

Answer 1

The concentration of the diluted KBr solution is 3 M.

Explanation:

Use the dilution equation `M_1V_1=M_2V_2`, where `M` is molarity in mol/L, and `V` is volume in liters.

Given/Known
`M_1="6.0 M"="6.0 mol/L"`
`V_1=450cancel"mL"xx(1"L")/(1000cancel"mL")="0.45 L"`
`V_2=900cancel"mL"xx(1"L")/(1000cancel"mL")="0.9 L"`

Unknown
`M_2`

Solution
Rearrange the dilution equation to isolate `M_2` and solve.
`M_1V_1=M_2V_2`

`M_2=(M_1V_1)/(V_2)`

`M_2=(6.0"mol"/"L"xx0.45cancel"L")/((0.9cancel"L"))="3 mol/L"="3 M"`