Кислоти та основи

We have been learning about naming compounds. Ionic compounds have the name of the metal followed by the anion with the -ide ending. For example, $NaCl$ is sodium chloride. The exception to the -ide ending is the oxoanions. The covalent molecules also use the -ide ending. But, the -ide ending is the more electronegative atom. Remember, more electronegative elements are further to the right of each period on the periodic table. We also add prefixes to denote the number of atoms. For example, the proper name for water ($H_{2}$$O$) is dihydrogen monoxide.

Now, we will look at acid and base nomenclature. Acids and bases are a unique class of molecules. Proton transfer is the distinguishing feature of acid-base reactions. Acids give up protons while bases receive protons. We need to know when something is an acid because that tells us how it will react. Therefore, acids and bases have unique naming conventions.

Rules for Naming the Acids

There are four steps to naming an acid.

1. To name an acid, we look at the -ide molecule in the covalent bond.
2. We change the -ide ending to -ic.
3. We add the prefix hydro to denote the hydrogen atom.
4. We add the word acid at the end.

Let's look at $HCl$ as an example.

1. In the covalent bond nomenclature, the chlorine atom would have the -ide ending.
2. We change the -ide ending to -ic. So, chloride becomes chloric.
3. We add the prefix hydro. So, it becomes hydrochloric.
4. We add acid at the end. We have hydrochloric acid.

Rules for Naming Oxoacids.

Recall that the oxoanions have unique nomenclature. There are four rules for naming oxoacids.

1. An oxoanion ending in -ate changes to -ic.
2. An oxoanion ended in -ite becomes -ous.
3. We keep all prefixes.
4. We add acid at the end.

Let's look at the chlorine oxoanions series.

• Chlorate, $ClO_{3}^{-}$, is the most common. We name the acid chloric acid ($HClO_{3}$) based on rules 1 and 4.
• Chlorite, $ClO_{2}^{-}$, has one less oxygen. We change it to chlorous acid ($HClO_{2}$) because of rules 2 and 4.
• Hypochlorite, $ClO_{2}^{-}$, has one less oxygen than chlorite. We name the acid hypochlorous acid ($HClO$) because of rules 2, 3, and 4.
• Perchlorate, $ClO_{4}^{-}$, has one more oxygen than chlorate. Its acid is perchloric acid ($HClO_{4}$) based on rules 1, 3, and 4.

A List of Common Acids

Your teacher may have you memorize the names and molecular formulas of some common acids. There are only seven strong acids. If you remember the seven strong acids, then you know anything else is a weak acid. I have listed a few of the common weak acids too.

Strong Acids

1. $HCl$-Hydrochloric acid
2. $HBr$-Hydrobromic acid
3. $HI$-Hydroiodic acid
4. $HNO_{3}$-Nitric acid
5. $HClO_{4}$-Perchloric acid
6. $HClO_{3}$-Chloric acid
7. $H_{2}$$SO_{4}$-Sulfuric Acid

Weak Acids

1. $HF$-Hydrofluoric acid. Unlike the other halogens, hydrofluoric acid is a weak acid. The hydrogen-fluorine bond is polar. So, hydrofluoric acid can hydrogen bond. Hydrogen bonding increases its stability. However, hydrofluoric acid is exceptionally corrosive. During dissociation, both the proton and the fluorine are very reactive.
2. $CH_{3}$$COOH$-Ethanoic acid. Ethanoic acid is a carboxylic acid. You will learn more about carboxylic acids in organic chemistry. It's commonly named acetic acid and is found in vinegar.
3. $H_{2}$$SO_{3}$-Sulfurous acid
4. $HNO_{2}$-Nitrous acid
5. $H_{3}$$PO_{4}$-Phosphoric Acid
6. $H_{2}CO_{3}$- Carbonic Acid

Naming Bases

We do not have any special rules for naming bases. The strong Bronstead bases have an ionic metal-hydroxide bond. Remember, hydroxide is a polyatomic anion. So, we follow the ionic bonding nomenclature. For example, NaOH is sodium hydroxide. The metal is almost always an alkali or alkaline-earth metal. In contrast, the transition metal hydroxides are not strong bases. Most transition metal hydroxides are insoluble. Many strong lewis bases are conjugates of weak acids. For the conjugate ions, we name them as ions. For example, the conjugate of acetic acid is the acetate ion. Weak bases are covalent molecules. So, we follow the covalent bonding nomenclature.

(Video) Naming Acids | How to Pass Chemistry

by Melissa Maribel

In this video, Melissa teaches you how to name acids based on their formulas. You'll also learn how to write the formula based on the name. Melissa will also show you some tricks you can use to help you do these problems more easily.

(Video) Bases Naming and Writing

by Sandy Lee

This video will teach you the steps to naming a base. Luckily, there aren't many rules to remember. Bases are metal hydroxides, so their names will usually be whatever metal is involved plus the word "hydroxide". One exception to this is ammonium ($NH_4$), which is not a metal.

Please note: This video incorrectly refers to $NH_4$ as ammonia instead of ammonium. The chemical formula for ammonia is actually $NH_3$.