@MataroPete, yes, that is what a chemist would say. 
@Goofyhoofy here is a practical exercise in salts.
If your garden tomatoes have blossom end rot it’s a sign they don’t have enough calcium. But common agricultural lime (crushed limestone which is calcium carbonate*) is slow to dissolve. You need a soluble, quick-acting calcium salt.
Dissolve an eggshell (or a Tums tablet) in vinegar, making sure that there is excess solid so the solution is not acidic.
Acid + base → salt + water
CH3COOH + CaCO3 —> CH3COO Ca (calcium acetate) + CO2 (bubbles) + H2O
Water the tomato plants with the solution of calcium acetate salt. That will heal the blossom end rot.
Wendy
*Quicklime (CaO) is made by heating limestone. Slaked lime has water added to quicklime – it’s Ca(OH)2