The document discusses acids and alkalis. It defines alkalis as bases with a pH over 7 and describes their characteristics as soluble in water, slippery feeling, and ability to cause chemical burns. Alkalis are formed from group 1 and 2 metals and are often hydroxides. Acids are defined as having a pH under 7, sour taste, and containing hydrogen and an oxide. Most acids are hydrogen compounds. When acids and alkalis are mixed, a neutralization reaction occurs where they cancel each other out, forming a salt and water. Carbonates react with acids in the same way, forming a salt, water, and releasing carbon dioxide.