Year 8 Science · Unit 3 · Lesson 4

Evidence of Chemical Reactions

Foundation Worksheet

Name
Date
Class

Learning Goals

Warm Up

Sort it!

Write each observation from the pool into the correct evidence category box.

Iron turns orange-brown Antacid tablet fizzes in water White solid appears in clear liquid Hand-warmer packet heats up Sparkler produces bright light Milk turns sour and smells different Explosion produces a loud bang Cold pack feels icy Silver coins turn black over time Vinegar + bicarb produces bubbles

Colour change

Gas produced

Precipitate formed

Temperature change

Light or sound

Your Turn

Match each clue to its description

Draw a line connecting each piece of evidence for chemical change on the left to its correct description on the right. Or write the matching letter next to each clue.

Evidence clue Your answer Description
Colour change A. A solid forms suddenly in a solution where none existed before
Gas produced (effervescence) B. The substance absorbs or releases thermal energy, detectable by temperature change
Temperature change C. A new substance forms with different light-absorbing properties
Precipitate formed D. Energy is released as visible light or audible sound during a vigorous reaction
Light or sound E. Bubbles of a new gas form in a liquid as a product of the reaction

Show What You Know

1. A student adds vinegar to bicarb soda. They observe bubbling and the container feels slightly cold. Name the two pieces of evidence for a chemical reaction and state what each piece tells you about the reaction.

Recall 2 marks

2. CSIRO bushfire scientists measure gas production and temperature rises when vegetation burns. Why do scientists collect multiple types of evidence rather than relying on a single observation to confirm a chemical reaction?

Recall 2 marks

Wrap Up

In one sentence, what was the main idea of this lesson?

HSCScience · Year 8 Science · Unit 3 · Lesson 4 · Foundation Worksheet