# OVERVIEW

5M hydrochloric acid can be prepared by diluting a concentrated 37% (w/w) stock solution of hydrochloric acid. A 37% (w/w) hydrochloric acid is available commercially and can be purchased from several suppliers. A liter (1000 ml) of 5M hydrochloric acid can be prepared by mixing 410.58 ml of 37% hydrochloric acid and 589.42 ml of distilled/deionized water. Below we describe the preparation process in detail.

# REQUIREMENTS

Reagents and solutions
37% (w/w) hydrochloric acid stock solution
Distilled/deionized water

Equipment and disposables
Beaker (1 Liter)
Magnetic stirrer
Fume hood

OBJECTIVE
Preparation of 1000 ml of 5M Hydrochloric Acid using concentrated stock solution (37%, w/w)

# PROCEDURE: Preparation of 5M Hydrochloric Acid

Precautions: Use personal protective equipment (lab coat, gloves, goggles, etc) for your safety and follow the guidelines of your institute.

Step 1: Calculate the volume of 37% (w/w) hydrochloric acid solution required for the preparation of 1000 ml of 5 M hydrochloric acid solution.

The molarity of 37% (w/w) concentrated hydrochloric acid solution is 12.178M (read more “Molarity of 37% (w/w) Hydrochloric Acid (HCl)” Use the dilution method to calculate the volume of concentrated stock solution required for the preparation of 1000 ml of 5M hydrochloric acid solution. The dilution method is described in detail in the post “Preparing Working Solution from Stock Solution by Dilution”.

Use the following formula

Cf x Vf = CS x VS

Cf (concentration of diluted solution) = 5M
Vf (volume of diluted solution) = 1000 ml
CS (concentration of stock solution) = 12.178 M
VS (volume of stock solution) = ? (unknown)

Place all values in the formula:

5 x 1000 = 12.178 x VS

VS = 5 x 1000/ 12.178 = 410.58 ml

So you need 410.58 ml of 37% (w/w) concentrated hydrochloric acid solution to prepare a 1 liter of 5M hydrochloric acid solution.

Step 2: Calculate the volume of solvent to be taken.

The final volume of diluted solution = 1000 ml
Volume of concentrated solution = 0.082 ml
Volume of solvent (water) required = 1000 – 410.58 = 589.42 ml

So you need to mix 410.58 ml of 37% hydrochloric acid with 589.42 ml of water to prepare 1000 ml of 1M hydrochloric acid solution.

Step 4: Transfer 589.42 ml of deionized/distilled water to a beaker/measuring cylinder. Add 589.42 ml of 37% concentrated hydrochloric acid stock solution and mix it to prepare a homogeneous solution.

STORAGE
The solution can be stored at room temperature. 