# How to make 0.5N HCl

## How to make 31% HCl into 0.5N standard solution

The density of 31% hydrochloric acid is 1.151g/mL and the concentration is 9.87N.

To match the 0.5N solution, set the volume of concentrated hydrochloric acid to V1, and the volume of dilute hydrochloric acid to V2, then:

V1 * 1.151g/mL * 31% = 0.5mol/L * V2 * 36.5g/mol (according to the mass of the solute during the dilution process)

Available: V1 / V2 = 0.051

That is if 1 L of 0.5 N dilute hydrochloric acid is to be prepared, 51% of concentrated hydrochloric acid (51 mL) is required.

After the calculation, follow the steps of preparing the solution (assuming that one liter of 0.5N diluted hydrochloric acid is prepared):

- Pipette 51.00mL concentrated hydrochloric acid with a pipette
- Dissolve in a beaker with a small amount of water, dissolve and transfer to a 1L volumetric flask; wash the beaker and transfer the washed solution to the volumetric flask.
- Make the volume bottle constant.
- Transfer the solution and label it.