Comparing Common Acids & Bases

Instructor: David Wood

David has taught Honors Physics, AP Physics, IB Physics and general science courses. He has a Masters in Education, and a Bachelors in Physics.

What are acids and bases? Learn what those terms mean, and how we measure them. Then discover some of the most common acids and bases you experience in your everyday life.

What are Acids and Bases?

Each food we eat tastes different, and there are many reasons for that: substances can be sweet, spicy, bland, bitter, or acidic. Understanding why things taste the way they do is pretty complicated. But there's one part of it that simpler: acidity. Whether it's foods you eat, or cleaning products around your house, every substance is either an acid, a base, or neutral. But what those terms mean?

Bottle of hydrochloric acid used in a science lab
Bottle of hydrochloric acid used in a science lab

An acid is a chemical that is sour tasting and corrosive. Strong acids can dissolve metals, and neutralize bases. Chemically, they have to contain positive hydrogen ions. A base on the other hand is a chemical that is a bitter tasting and caustic. Bases can neutralize acids, and chemically they contain hydroxide ions (negative ions made up of an oxygen and hydrogen atom bonded together). A neutral substance is something right in the middle - is not quite an acid, and not quite a base.

Acids are corrosive
Acids are corrosive

We measure acids and bases on a scale called the pH scale, where 7 is neutral, a pH larger than seven is a base, and a pH smaller than seven is an acid. This can be tested using something called indicator paper, which turns different colors depending on pH: red for acid, blue for a base, and green for neutral.

So that's the difference between acids, bases, and neutral substances. But what are examples of each of these? What common substances we find in our daily lives are acids and bases? Let's take a look.

Common Acids and Bases

We said that acids are sour and corrosive, so that includes things like lemon juice (with a pH of 2) and vinegar (with a pH of 3). But contrary to popular belief, even milk is slightly acidic. There are also lots of household products that are acidic, like floor cleaners and toilet bowl cleaners, which tend to have a pH between zero and three.

However cleaning products are more likely to be bases, since the caustic properties of bases can be useful. One of the strongest examples is chlorine bleach, which has a pH between 11 and 13, and ammonia which has a pH between 11 and 12. But baking soda is also a base (with a pH of around 9), as is dish soap (7-8). When it comes to food, bases are things like egg whites (8.5), and some vegetables like spinach, garlic, and broccoli, though all foods that are bases are not strong bases.

Chart showing examples of acids and bases
Chart showing examples of acids and bases

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