What are Acids and Bases

Some foods we eat taste sour or are acidic such as lemon juice, sour milk, and vinegar, and some taste bitter or are basic such as baking powder, mustard, or medicines.

Acids and bases are chemicals that are grouped by scientists because they have similar properties. Many substances can be classified as either an acid or a base.

What is an acid?

Acids are substances that taste sour, react with some metals (often corroding them), and react with bases.

Lemon juice is an acid.


What is a base?

Bases are substances that taste bitter, feel slippery, and react with acids.

Many cleaners such as soap are made from bases.


What is a neutral substance?

Substances that are not acidic and not basic are called neutral substances.

Pure water is an example of a neutral substance.



View this video for an overview of acids and bases. 
 


  Dentistry Connection

 Acid can destroy the enamel on your teeth. After a meal, bacteria in your mouth break down food to produce acids. The enamel on your teeth is destroyed by acid. Once it is destroyed, the bacteria can get inside the tooth and cause tooth decay. The best way to prevent this chemical reaction from happening is to brush and floss your teeth after every meal and avoid eating sugary foods which produce the most acid.
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Just as hot and cold are two extremes in temperature, acid and base are two extremes in chemical reactions.  Just as combining hot and cold water makes temperature even out, combining an acid and base cancels the effect of the acid or base. Combining baking soda and vinegar is a common example of a chemical reaction between an acid and a base. Sometimes, people take an antacid for an upset stomach. The antacid is a base that reacts with the stomach acid to relieve the discomfort. Acid-base reactions are a common type of chemical reaction.

Not all acids and bases are natural. If you do not know whether a substance is an acid or base or neutral, should you taste it? Or touch it to see if it feels slippery?

NEVER put an unknown chemical in your mouth or on your skin! Acids and bases can be extremely strong chemicals that burn your skin or make you seriously sick. Instead of tasting or touching to tell if something is an acid or a base, an indicator can be used.




  Technology Connection

Fireworks use the science of chemistry in multiple ways. When any substance is burned, it has its own characteristic colour. The various colours produced by fireworks are caused by the chemical reaction of burning.

Also, a salt is a compound that is created when a base joins an acid. A type of salt called potassium nitrate is used to make fireworks. View this Science of Fireworks video that shows just how this works.

If you want to see an even more detailed and extensive explanation of putting on a major fireworks display, view Behind the Scenes at a Fireworks Display.


  Environmental Connection

 People use the salt calcium chloride to melt the snow and ice on roads and sidewalks.

But is using salt to melt ice a good solution? Calcium chloride causes concrete to pit, crack, and flake. It rusts cars more quickly. More seriously, when snow melts, salt leaches into the ground. In the soil, salt can stop plants and trees from growing. In the water, salt can kill aquatic life. The newspapers have various stories about the effects of calcium chloride. Salt Reductions   Pets Salt RustWinter Roads

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