Making a soluble salt (Method B)

Metal Hydroxide + Acid makes Salt + Water
Metal Carbonate + Acid makes Salt + Water + Carbon dioxide

To keep things clear, we call the "metal hydroxide / metal carbonate" "X"

We will add X to the acid.

X reacts with the acid so if any acid is present, X will continue to react.

If there is too much X, X will dissolve in water and so it will not be noticeable.

So, we need to do an experiment to find out the exact quantities of each that we need. Measure out some acid. Add an indicator to it. Add X to the acid until the indicator changes colour. Repeat the experiment using the same amount of acid and X but with no indicator.

This will leave a solution of the desired salt. Finally we need to evaporate the water (heat it to start with but let the crystals form slowly so that they are formed in better quality).

So it only remains to choose the exact combination. Sulphates come from sulphuric acid

Nitrates come from nitric acid

Chlorides come from hydrochloric acid

Try to work out how you would make these salts:

sodium sulphate, potassium chloride, barium nitrate