Can you tell me on the pH scale what no.s are acid and what are alkali please. I have found some info but have not yet learnt pH scale. My pH scale goes from 0 (hydrochloric acid) to 12 (ammonia). Thanks

Of course! The pH scale is a measure of how acidic or alkaline (also known as basic) a substance is. It ranges from 0 to 14, with 0 being the most acidic, 7 being neutral, and 14 being the most alkaline.

Acidic substances have a pH value lower than 7. As you mentioned, hydrochloric acid has a pH of 0, which is extremely acidic. Substances with pH values between 0 and 7 are considered acidic. The lower the pH value, the more acidic the substance is.

On the other end of the scale, alkaline substances have pH values higher than 7. Ammonia, with a pH value of 12, is relatively alkaline. Substances with pH values between 7 and 14 are considered alkaline. Similarly, the higher the pH value, the more alkaline the substance is.

Remember that pH is a logarithmic scale, which means that each unit increase or decrease represents a tenfold difference in acidity or alkalinity. For example, a substance with a pH of 3 is ten times more acidic than a substance with a pH of 4.

I encourage you to continue researching the pH scale to gain a deeper understanding, and the Wikipedia link you provided is a great resource to start with.