NAMES TO KNOW
Here are a couple of definitions you should know:Acid: A solution that has an excess of H+ ions. It comes from the Latin word acidus that means "sharp" or "sour".
Base: A solution that has an excess of OH- ions. Another word for base is alkali.
Aqueous: A solution that is mainly water. Think about the word aquarium. AQUA means water.
Strong Acid: An acid that has a very low pH (0-4).
Strong Base: A base that has a very high pH (10-14).
Weak Acid: An acid that only partially ionizes in an aqueous solution. That means not every molecule breaks apart. They usually have a pH close to 7 (3-6).
Weak Base: A base that only partially ionizes in an aqueous solution. That means not every molecule breaks apart. They usually have a pH close to 7 (8-10).
Neutral: A solution that has a pH of 7. It is neither acidic nor basic.
WHAT REALLY HAPPENS
What really happens in those solutions? It gets a little tricky here. We'll give you the straight answer. Acids are compounds that break into hydrogen (H+) ions and another compound when placed in an aqueous solution. Bases are compounds that break up into hydroxide (OH-) ions and another compound when placed in an aqueous solution.Let's change the wording a bit. If you have an ionic compound and you put it in water, it will break apart into two ions. If one of those ions is H+, the solution is acidic. If one of the ions is OH-, the solution is basic. There are other ions that make acidic and basic solutions, but we won't be talking about them here.
That pH scale we talked about is actually a measure of the number of H+ ions in a solution. If there are a lot of H+ ions, the pH is very low. If there are a lot of OH- ions, that means the number of H+ ions is very low, so the pH is high.
Think about it for a second. Why would a liquid with high levels of NaOH be dangerous and very basic? The Na-OH bond breaks in solution and you have sodium ions (+) and hydroxide ions (-). The sodium ions don't really pose a danger in solution, but there are a huge number of hydroxide ions in solution compared to the hydrogen ions. All of those excess OH- ions make the pH super-high and the solution will readily react with many compounds. The same thing happens on a less dangerous scale when you add baking soda to water. OH- ions are released in the solution. The numbers of OH- are greater than the H+ and the pH decreases.
That's basically it. (Ha Ha, get it?)