Nikki has a master's degree in teaching chemistry and has taught high school chemistry, biology and astronomy.
If we approach conjugate bases like experienced detectives, the first place to investigate them is the last place we would expect them to be: in the world of acids. Chemically speaking, acids are the opposite of bases. In general, acids are substances that break apart in water to produce hydrogen ions (H+). They have low pH values, taste, and smell sour, and can be corrosive.
Conjugate bases are intimately related to acids. A conjugate base is the particle that is left over after the acid loses its hydrogen ion. Most of the time, conjugate bases are negatively charged and have high pH values.
There are as many conjugate bases as there are acids. When an acid loses a hydrogen ion, its conjugate base is produced. An acid and its conjugate base have the same formula but with one minor difference: an acid has one more hydrogen ion than the conjugate base does.
Let's take hydrochloric acid (HCl), a fairly common acid. Since HCl is an acid, when put into water it produces hydrogen ions (H+). After the acid loses its hydrogen ion, the negatively charged chloride ion (Cl-) is left over. The chloride ion (Cl-) is the conjugate base of HCl.
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Take a look at this chart of acids and their conjugate bases. Do you notice any patterns that describe the difference between an acid and its conjugate base?
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For example, did you notice how the conjugate bases resemble the acids they were formed from (except that they are missing a hydrogen ion (H+), making them negatively charged)?
We can show the relationship between an acid and its conjugate base using this expression: HA --> H+ + A-, where HA is the acid, H+ is the hydrogen ion, and A- is the conjugate base of the acid.
Some conjugate bases are stronger than others, meaning they attack or attach to hydrogen ions with varying strengths. Strong conjugate bases attack and attach very well to hydrogen ions. Weak conjugate bases don't attack or attach to hydrogen ions very well.
Conjugate bases are also produced in an acid-base reaction. In an acid-base reaction, the reacting acid loses its hydrogen ion to the reacting base, producing a conjugate base and other products.
For example, in this simplified acid-base reaction, the acid HF loses its hydrogen to the base OH, producing water, shown as HOH, and the conjugate base F, both of which have a negative charge.
In this second acid-base reaction, HNO subscript 3 loses its hydrogen to water, which is the base in this reaction. NO subscript 3, the conjugate base of HNO subscript 3, is produced.
A conjugate base is what's left over after an acid loses a hydrogen ion. In general, conjugate bases are negatively charged and have higher pH values.
Every acid has a conjugate base. The conjugate base of an acid has the same formula except that the acid has one more hydrogen ion.
Conjugate bases may be produced when an acid dissociates in water or during an acid-base reaction.
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