pH Scale

acid

Substance that has a pH less than 7 and donates a hydrogen ion (H+, a proton) to a solution. Few OH⁻ and many H⁺. Turns cabbage juice indicator pink/red/orange.

base

Substance that has a pH greater than 7 and donates a hydroxide ion (-OH) to a solution. Many OH⁻ and few H⁺. Turns cabbage juice indicator blue/green/yellow.

neutral

Substance with a pH of 7 and equal amounts of hydrogen (H+) and hydroxide (-OH) ions. Does not change the color of cabbage juice indicator (stays purple).

pH scale

A system for measuring the amount of hydrogen ions (H+) in a solution to determine how acidic or basic it is on a range of 0-14.

examples of weak acids

urine, soda (carbonated water), rainwater, coffee, orange juice

examples of stronger acids

lemon juice, gastric (stomach) juices, tomato juice, vinegar

examples of stronger bases

bleach, ammonia

examples of weak bases

blood, tears, baking soda, soap

neutralization

A reaction between an acid and base, bringing the solution closer to neutral.