What is the difference between an acid and a base?

Answer

base is any thing which has a capability to abstract a proton .

Using the simplest definition, an acid is something when when added to water releases hydrogen ions (H⁺), also called protons. A base, or an alkali, is something that when added to water releases hydroxide (OH^-) ions.

The strength of a basic (or alkaline) or acidic solution is measured using the pH scale. A pH of 7 is perfectly pure neutral water (neither acidic nor basic), and pH below 7 is acidic, and a pH above 7 is basic.

There is another definition which says that an acid releases H₊ and a bases remove H⁺ from water. This definition is a bit more general than the first one above. Note that releasing OH^- is actually exactly the same as removing H⁺. This is because when OH^- mixes with H⁺, they form neutral H₂O, and so for every OH^- released, one H⁺ is removed by combining them into water.

The final definition of an acid and base is the most general, but the hardest to understand conceptually, and it is not always taught in high school because of this. According to this definition, acids are electron pair acceptors, and bases are electron pair donors.

Note that in all cases, acids and bases have essentially opposite definitions. That is why when you add and acid to a base, they tend to cancel each other out and make a neutral solution!

Answer

Acids cause solutions to have extra hydrogen ions (H⁺), bases cause it to have extra hydroxide ions (OH^-).

In just regular water, there are always a few broken water molecules floating around, hydrogens missing their electron (H⁺) and hydrogen-oxygen groups with an extra electron (OH^-). Normally these exist in equal amounts, with a concentration each of 10^-7 moles per liter. Take -log₁₀(H⁺) concentration, and you get pH, so neutral water has a pH of 7.

Add an acid to water, such as hydrochloric acid (HCl) to the water, and there will be a surplus of H⁺ ions, like maybe 100 times as many as before, or 10^-5 moles per liter, so now the solution has a pH of 5.

On the other hand, add a little lye (NaOH) and you have a surplus of OH^-. Now there might be 100 times fewer hydrogens than there were before, so or 10^-9 of them, so now the pH is 9.

See the Web Links and Related Questions for more information about acids and bases.

See Related Links

See the Related Link for "Wikipedia: Acid" to the left for more information

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First answer by Pgr-fw. Last edit by Jyoti.kunu. Contributor trust: 7 [recommend contributor]. Question popularity: 57 [recommend question]