Play > ChemMystery > Properties of Acids, Bases and Neutrals

Detective Surelick

Make Your Own Acid/Base Indicator

See related GEMS teacher's guide Of Cabbages and Chemistry

See related School Program
Of Cabbages and Chemistry

 

Properties of Acids, Bases and Neutrals

Taste: Have you ever taken a bite out of a sour lemon? When you taste something sour, your face kind of looks like this - *. Lemon juice is an acid and acids can taste sour. Baking soda has a bitter taste that most people don't like - *. It is an example of a base and bases can taste bitter. Water is not an acid or a base, it is neutral and has no particular taste. Please don't ever taste strong acids or strong bases or any other chemicals that are not food!

Feel: What happens if you're slicing lemons and some juice get into a cut on your finger? YOW! It stings. Acids sting cuts. If you've ever spilled bleach or soap on the floor, you may have noticed that it is slippery. Bases such as bleach and soap are slippery. Our neutral substance, water, would be a good choice for cleaning up acids and bases because it doesn't sting and it's not slippery. Please don't ever touch strong acids or strong bases because they can be harmful to your skin and may damage sensitive tissues such as your eyes.

Examples of acids, bases and neutrals
What are some common acids, bases and neutrals? These are some acids you may be familiar with: lemon juice, vinegar, orange juice, carbonated beverages, stomach acid and battery acid. Do the food items on the list taste and feel like acids? These are some bases you may have seen: baking soda, bleach, ammonia, drain cleaner and soap. Some neutrals are: water, milk and hand lotion.

Chemical Effects:
You may be wondering what acids and bases do to other chemicals. Acids dissolve metals - tomato sauce in an aluminum pan, break up proteins - marinating meat, conduct electricity - battery acid and dissolve carbonate compounds - bacterial acid making cavities on teeth. Bases and acids neutralize each other. Mixing equal amounts of similar strength acids and bases produces a neutral substance

Measuring Acids and Bases
You have probably been told not to taste or touch strong acids and bases. So how do we know how strong these chemicals are? The pH scale is a tool for measuring acids and bases. It is an expanding scale that goes from 0-14. The lower the number the more acidic the substance, a pH of 7 right in the middle is neutral and the higher the number the more basic the substance. The color of the pH paper matches up with the numbers on the pH scale to tell you what kind of substance you are testing.

The Power of Hydrogen
The abbreviation pH stands for Ůthe power of hydrogenÓ because it is actually a measure of the number of hydrogen ions or protons in a solution (pH = -log[H+] or pH of 7 in water means there are 10-7 moles of H+ ions per liter). Acids release hydrogen ions ( positively charged particles) from solution and bases remove hydrogen ions from solution. Because the pH scale is logarithmic, this means a substance of pH 5 is 10 times more acidic than a substance of pH 6.