Acids and Bases

SNC2P

What do Lemon Juice and Vinegar have in common?

What do Baking Soda and Drain Cleaner have in common?

• These substances can be grouped as either acids or bases. Chemists use acids and bases as a way to classify substances. Acids and bases are common chemical compounds that can be grouped according to their chemical and physical properties.

Acids

• Substances classified as acids have specific properties. The chemical formula contains a Hydrogen Ion (H+) at the start – example HCl (hydrochloric acid). The chemical name includes the word “acid”. Acids are soluble in water. Acids dissociate into hydrogen ions H+ when dissolved in water. They taste sour. They will conduct electricity in solution.

Acids

• You must be careful with acids. Acids are corrosive and can be dangerous to the environment

Common Acids

Acetic Acid

(Vinegar)

HC2H3O2(aq)

Citric Acid HC6H7O7(aq)

Ascorbic Acid HC6H7O6(aq)

Carbonic AcidH2CO3(aq)

Acetylsalicylic acid (ASA)

HC9H7O4(aq) Asprin

Salad Dressings

Lemons, Limes, etc.

Vitamin C (Oranges, etc.)

Carbonated Drinks

Bases

Substances classified as bases have specific properties. The chemical formula usually contains a hydroxide ion (OH-) at the end – example sodium hydroxide, NaOH. The chemical name includes the word “hydroxide”. Ammonia is one exception to this rule. Ammonia, NH3 is a base and does not contain the hydroxide ion.

Bases

• Bases dissociate into hydroxide ions, OH- when dissolved in water. They taste bitter. They will feel slippery to touch. They will conduct electricity in solution. Chemists use the word ALKALINE to describe solutions that are basic.

Common Bases

Sodium hydroxide

NaOH(aq)

Potassium hydroxide

KOH(aq)

Aluminum hydroxide

Al(OH)3(aq)

Ammonium hydroxide

NH4OH (aq)

Sodium bicarbonate

NaHCO3(aq)

Window cleaners

Cleaners, making paper

Soap, cosmetics

Used to make baked goods rise.

Heartburn medications

Indicators:

• Tasting and feeling are not tests used by chemists to determine whether or not a substance is an acid or a base. Both can be extremely dangerous depending on the substance.

• Instead, chemists use a dye called an indicator that changes colour depending on what the solution is.