Question

QUESTION 4 [14 marks]
QUESTION 4.1
A Grade 11 class investigates the relationship between temperature and volume
of a fixed amount of gas. The learners take a balloon filled with gas and dunk it
into ice water, and water that has been heated. They then measure the diameter
of the balloon.
Figure 1: balloon experiment.
Question 4.1.1 [2 marks]
Write a suitable hypothesis for this investigation.
Question 4.1.2 [2 marks]
Identify the dependent and independent variables.
Question 4.1.3 [2 marks]
Identify 2 constant variables.
QUESTION 4.2
The graph for their results is drawn below.
Graph 1:Temperature vs Volume
Question 4.2.1 [1 mark]
Which law is being investigated by the grade 11 class?
Question 4.2.2 [2 marks]
Give TWO reasons why the graph does not start at the origin.

Answer 1

### QUESTION 4.1

#### Question 4.1.1 [2 marks]
**Hypothesis:** As the temperature increases, the volume of the gas in the balloon will also increase.

#### Question 4.1.2 [2 marks]
- **Independent Variable:** Temperature of the gas (measured by the temperature of the water)
- **Dependent Variable:** Volume of the gas in the balloon (measured by the diameter of the balloon)

#### Question 4.1.3 [2 marks]
Two constant variables could be:
1. The amount of gas inside the balloon (fixed quantity).
2. The type of gas used in the balloon (ensuring it's the same for each trial).

### QUESTION 4.2

#### Question 4.2.1 [1 mark]
The law being investigated by the Grade 11 class is **Charles's Law**, which states that the volume of a gas is directly proportional to its absolute temperature at constant pressure.

#### Question 4.2.2 [2 marks**
Two reasons why the graph does not start at the origin could be:
1. There is a minimum volume required for the gas to exist, even at very low temperatures, due to the physical properties of gases.
2. The balloon may not be able to reach a volume of zero because of its elasticity and the presence of gas particles that cannot be compressed to a vanishingly small volume under normal conditions.