Alkali/ˈælkəlaɪ/ Definition 1 of 3Pro Tip 1/3Neutralization Reaction Alkali is used to neutralize acids, a common reaction in chemistry. Adding an alkali can neutralize vinegar's acidity. Pro Tip 2/3Common Products Many cleaning products contain alkali substances that react to stains. The bottle says the cleaner has alkali to fight grease. Pro Tip 3/3pH Scale Alkalis have a pH greater than 7 and feel slippery to the touch. This alkali solution turned the pH paper blue.