The instructions below are only good for concentrated Hydrochloric from

35-38% solution with a specific gravity of 1.18 and a molar mass of 36.46 g/mol.

The concentration of Hydrochloric acid decreases over a long period of time; as the gas diffuses into the atmosphere. It is advisable to keep stocks in secured glass containers and should be kept properly inside the laboratory. It is best to store them in an outside stock room if there is any in your school.

Do not attempt diluting Hydrochloric acid if it is your first. Ask a colleague or from a more experienced laboratory staff to help you. Do not allow students to dilute concentrated solutions, but you can demonstrate this in the science laboratory in order for them to understand the procedure correctly. However, you may ask them to dilute further diluted solution from 1M and lower.

**Instructions:**

- Wear gloves and goggles
- Ideally, use fume cupboard if it is available in your laboratory.
- Measure the required volume of concentrated HCl in a measuring cylinder. ( Consider the table below.
- Add this to about two-thirds of the final volume of water in a separate beaker.
- Stir the solution properly.
- Transfer the solution into a larger measuring cylinder and add water to the required level.
- Mix thoroughly. And it’s done.

**The best way is to make large amount of 2M and dilute it further to lower concentration as in the table below.**

**GUIDE TABLE**

Required Diluted Concentration | Required Volume of Solution | ||

| 500 ml | 1000 ml | 2500 ml |

| 84 ml | 167 ml | 417 ml |

| 42 ml | 84 ml | 209 ml |

| 21 ml | 42 ml | 105 ml |

| 17 ml | 34 ml | 84 ml |

| TEN-FOLD of | ||

| TEN-FOLD of |

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