The substance commonly known as „salt“ is sodium chloride, just one among a great number of other salts. Several of them are familiar colorless crystals, well soluble in water and with that typical „salty“ taste. Others, though, have completely different properties: Some salts have different colors, some can actually change the water´s pH value to acidic or alkaline when dissolved. For centuries, alkaline salts such as potassium or sodium carbonate ("potash" or "soda“) were used to produce soap out of animal fats, a process which was carried out by professional soap boilers:

Why can a salt be alkaline? Why can a salt be sour? Find out in this activity!