To prepare a soluble salt from an acid and an alkali, you will utilize a process known as neutralisation.

Neutralisation is a chemical reaction that occurs when an acid reacts with an alkali. During this reaction, the acid and alkali combine to produce a salt and water. This process is classified as a double displacement reaction, where the hydrogen ions ($H^+$) from the acid react with the hydroxide ions ($OH^-$) from the alkali to form water ($H_2O$), while the remaining ions form the salt.

To successfully prepare a soluble salt, it is essential to select an appropriate acid and alkali. The specific type of salt produced will depend on the chosen acid and alkali. For instance, mixing hydrochloric acid ($HCl$) with sodium hydroxide ($NaOH$) will yield sodium chloride ($NaCl$), a common soluble salt.

The procedure begins with the careful addition of the alkali to the acid while stirring the mixture. You should continue adding the alkali until the acid is completely neutralised. The endpoint of neutralisation can be determined using an indicator, such as litmus paper, which changes color when the solution reaches a neutral pH. It is crucial to add the alkali gradually to prevent an excess of alkali in the final solution.

Once the acid has been neutralised, a solution of the salt in water will remain. To isolate the solid salt, you will need to remove the water. This can be accomplished by gently heating the solution to evaporate the water, which will leave behind the solid salt.

Always prioritize safety when conducting this process. Be sure to wear safety goggles and gloves, and work in a well-ventilated area. If you have any uncertainties, do not hesitate to seek assistance from your teacher or another responsible adult.