Physical and chemical change

• Scien
• Secondary Education
• Age 13

Physical change

Chemical change

Let's answer

• What types of changes did you observe while sorting the flashcards?

Let's answer

How can you identify a physical change? What evidence helped you decide it was a physical change?

Are all physical changes reversible? Why or why not?

Physical and Chemical change

Learning Objective

Differentiate between chemical and physical changes.

 

Evaluate and list the characteristics of physical and chemical change.

LO: Differentiate between chemical and physical changes.

Evaluate and list the characteristics of physical and chemical change.

• Group Activity :Analyse and observe the changes happened. Complete the task sheet provided.
• Activity 1: To Observe the sample of apple and potato provided. 
• Activity 2: Demonstration of the reaction between baking soda and vinegar
• Acticity 3: • Burning of Magnesium Ribbon: Think back to the experiment did in the last lab period.

Task Sheet – Observing and Understanding Changes

Part 1: Observation – Browning of Apple Slice

You are given a piece of browned apple. Observe carefully and answer:

 1. What do you see on the apple slice?

2. How is it different from a freshly cut apple?
   
3. What do you think caused the apple to turn brown?
    
4. Do you think this is a physical or chemical change? Why?

   

Part 2: Demonstration – Vinegar and Baking Soda Reaction

Observe the teacher’s demonstration carefully.

5. What did you see when vinegar and baking soda were mixed?

    

6. What signs showed that a chemical change took place?

   ☐ Bubbles    ☐ Color change  ☐ Smell  ☐ Heat

7. What gas do you think was produced?

    

8. Do you think this change can be reversed? Why or why not?

    

 Part 3: Recall – Burning of Magnesium Ribbon

Think back to the experiment did in the last lab period.

9. What happened when the magnesium ribbon was burned?

    

10. What were the signs that a chemical change had occurred?

    

11. What new substance was formed? What did it look like?

    

Define a chemical change and list out observable evidences of a chemical change.

Characteristics of chemical change

No new product is formed

New product is formed

Evolution of gas

Generation of light and sound

Only physical properties like shape, size, colour etc. of the substance changes.

Generation of characteristic smell

Only chemical properties and composition of the substance changes.

Physical change

Chemical change

What happens during a chemical change?

1. The substance only changes its shape
2. The change can always be reversed
3. A new substance is formed
4. The change is always temporary

Freezing water into ice is considered a physical change because:

1. It creates a new substance
2. It cannot be reversed
3. It involves a color change
4. No new substance is formed

Which of these is an example of both physical and chemical change?

1. Dissolving sugar in tea
2. Burning a candle
3. Melting wax
4. Chopping onions

What is the key difference between a physical change and a chemical change?

1. Physical change creates new substances, chemical change does not
2. Chemical changes are always reversible
3. Chemical changes result in new substances with different properties
4. Physical changes always involve heat

Which of the following statements is TRUE about physical changes?

1. They always release heat
2. They involve a change in chemical composition
3. They often include color change
4. They do not produce new substances

TextChoose any three questions in a row—horizontally or diagonally—from the choice board, aiming for the highest total score.

Extension/ HW

The Taj Mahal and the Great Wall of China are iconic monuments that have withstood the test of time, yet they are not immune to weathering and texture changes. Analyze the types of physical and chemical weathering processes affecting these monuments. How do these processes alter the texture and appearance of the structures over time? Propose strategies for preserving such historical monuments, considering both scientific and cultural factors.

Create a Venn diagram to compare the characteristics of physical and chemical change.

Challenge Your Understanding 

1 .The liquified petroleum gas (LPG) is the gas which is used for cooking at home. In the cylinder, it comes as a liquid. When it comes out from the cylinder, it become a gas (Change A). Then it burns (Change B). Identify the changes and write the differences between changes A and B. 

2.  The toasted bread has undergone a chemical change because it cannot be converted to bread again (irreversible change). What does the toaster do? List the evidences for the changes that occurred.

3.  Evaluate the nature of the alloying process: should it be considered a physical change or a chemical change?