Metal Carbonates and Their Reactions With Acids

1. What Are Metal Carbonates?

A metal carbonate is a compound made from:

• a metal element, and

• a carbonate group, which contains carbon and oxygen together.

A metal carbonate is usually a solid and often appears as a white or colored powder.

Examples of metal carbonates (written in words only):

• calcium carbonate – found in chalk, limestone, and marble

• sodium carbonate – also called washing soda

• magnesium carbonate

• copper carbonate – usually green in color

2. What Happens When a Metal Carbonate Reacts With an Acid?

When any metal carbonate comes into contact with an acid, a very predictable reaction occurs. The products are always:

✔ a salt

✔ water

✔ carbon dioxide gas

This reaction produces bubbles or fizzing, which is the escaping carbon dioxide gas.

3. Word-Based Reaction Pattern

metal carbonate + acid → salt + water + carbon dioxide

This always happens, no matter what metal carbonate or what acid is used.

4. Examples (Word-Only)

A. Calcium carbonate reacting with hydrochloric acid

Products formed:

• calcium chloride (a salt)

• water

• carbon dioxide gas

B. Magnesium carbonate reacting with sulfuric acid

Products formed:

• magnesium sulfate (a salt)

• water

• carbon dioxide gas

C. Copper carbonate reacting with nitric acid

Products formed:

• copper nitrate (a salt)

• water

• carbon dioxide gas

5. How To Test for Carbon Dioxide

You can confirm the gas using limewater:

• When carbon dioxide is bubbled through limewater, the liquid becomes cloudy or milky.

• This is because a white solid is formed in the mixture.

This change is the classic test for carbon dioxide.

6. Why Do Metal Carbonates React With Acids?

Metal carbonates contain the carbonate group, which reacts strongly with acids.Acids supply hydrogen ions, and carbonates break down when they meet these ions.

The carbonate group decomposes into:

• carbon dioxide gas

• water

The metal part of the carbonate and the leftover part of the acid combine to form a salt.

7. Uses and Applications

1. Antacid tablets

Magnesium carbonate is used to calm excess stomach acid through neutralization.

2. Building and erosion

Acid rain slowly dissolves calcium carbonate in rocks and buildings made from limestone or marble.

3. Identifying unknown substances

A fizzing reaction with acid is used in labs to confirm whether a substance is a metal carbonate.

4. Environmental chemistry

Carbon dioxide release and carbonate interactions play roles in ocean chemistry and geology.