Change of State | Acids and Bases | Grade 5 Science and Technology

Observe the image below
- The process by which a solid when heated turns into liquid is called melting.
When burning, a candle melts into liquid candle wax.

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- Melted wax ice water and cooking fat solidify when cooled. This is called solidification.
During cold weather, liquid cooking oil solidifies.

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- Naphthalene gas changes to solid directly. This is called deposition.

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- When gas (water vapour) is cooled, it changes to liquid. This is called condensation.

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There are solids that change into gas when heated. This process is known as sublimation.

Changes of State in Everyday Use

Acids

Examples of substances that are acidic

• Lemon Juice
• Vinegar
• Sour Milk
• Orange Juice

Properties of Acids

- They turn a blue litmus paper red.
- They taste sour.
- They corrode metal (strong acids).

Uses of Acids

- Acids are used in making juices.
- Acids are used in manufacturing industries in making fertilisers, paints, dyes and chemicals.
- Used in making car batteries.

Safety Precautions When Dealing With Acids

1. Wear protective gears (goggles, long sleeved clothes and gloves) when using acids and bases.
2. Always label acids and bases.
3. Never touch acids and bases with your bare hands.

Bases

Examples of substances that are acidic

• Bar Soap
• Wood ash
• Baking Powder
• Anti-acid

Properties of Bases

- They turn a red litmus paper blue.
- They taste bitter.
- They feel slippery.

Uses of Bases

- Used in making soap.
- Used in making paper and tooth paste.
- Used in making baking powder.
- Used in making anti acid tablets which are taken when one has excess gas in their stomach.