How much water must we add to a 10 ml sample of HCl with a concentration of 0.5 mol L1 to bring about a tenfold dilution?

How much water must we add to a 10 ml sample of HCl with a concentration of 0.5 mol L1 to bring about a tenfold dilution?

1. The final concentration of the HCl solution which has a tenfold dilution = (0.5 x 1/10) = 0.05 mol/L.
2. Let the final volume of this HCl solution = V ml.
3. This volume can be determined by the dilution formula of C1 x V1 = C2 x V2, where C1 = 0.5 mol/L, V1 = 10 ml, C2 = 0.05 mol/L and V2 = V ml.
4. Hence, 0.5 x 10 = 0.05 x V. On solving for V = (0.5 x 10)/0.05 = 100 ml
5. Therefore, the volume of water to be added = (100 - 10) = 90 ml
6. Please add the 10 ml of 0.5 mol/L HCl solution slowly to 90 ml of water and mix well - always add acid to water.