Required Practical: Density

Question 1

What is the aim of the required practical on density?

Answer 1

To measure the density of various materials — including regular solids, irregular solids, and liquids.

Question 2

What is the general approach when investigating density?

Answer 2

• Record the mass accurately.
• Measure and observe the mass and volume of different objects.
• Use appropriate apparatus and methods to measure volume and mass.

Question 3

What equipment is needed to measure the density of a regular object?

Answer 3

• Ruler (for larger objects)
• Vernier calipers (for smaller objects)
• Mass/top-pan balance

Question 4

What are the steps for finding the density of a regular-shaped object like a box?

Answer 4

1. Measure the length, width, and height using a ruler or vernier callipers, depending on the size of the object.
2. Multiply these to calculate the volume.
3. Use a mass/top-pan balance to measure the mass of the box.
4. Apply the values to the density equation.

Question 5

What specific method is used for a regular solid like a steel cube?

Answer 5

1. Measure the length (l), width (w), and height (h) of the cube using a ruler.
2. Measure its mass on a top pan balance.
3. Calculate its volume using (l × w × h).
4. Calculate the density using ρ = m / V.

Question 6

How is the density of a regular metal sphere measured?

Answer 6

1. Use vernier calipers to measure the diameter.
2. Divide the diameter by two to get the radius.
3. Measure the mass using a top pan balance.
4. Calculate the volume of the sphere using: V = (4/3)πr³
5. Use ρ = m / V to calculate its density.

Question 7

What equipment is needed to measure the density of an irregular object?

Answer 7

• Mass/top-pan balance
• Measuring cylinder
• Eureka can (displacement can)

Question 8

What technique is used to measure the volume of an irregular object, and why?

Answer 8

The displacement technique — where the volume of displaced water equals the volume of the object.

Question 9

What are the steps for finding the density of an irregular object (like a key or stone)?

Answer 9

1. Measure the mass using a mass/top-pan balance.
2. Fill a Eureka can with water to the brim.
3. Place a measuring cylinder under the spout.
4. Submerge the object — displaced water flows into the measuring cylinder.
5. The volume of water displaced = volume of the object.
6. Use mass and volume in the density equation.

Question 10

How can eureka cans cause experimental errors?

Answer 10

If the eureka can is not set up correctly, extra drops of water may dribble out before use, giving incorrect volume readings.

Question 11

What equipment is used to measure the density of a liquid?

Answer 11

• Measuring cylinder
• Mass/top-pan balance

Question 12

What are the steps for finding the density of a liquid (e.g., water)?

Answer 12

1. Place the measuring cylinder on the balance and record its mass.
2. Pour 50 cm³ of water into the cylinder and measure the new mass.
3. Subtract the first mass from the second to find the mass of the water.
4. Use the volume (50 cm³) and the mass in the density equation.

Question 13

What is the relationship between mL and cm³?

Answer 13

1 mL = 1 cm³

Question 14

Why are density measurements subject to experimental error?

Answer 14

Because of differences in:
- Calibration of balances
- Resolution of measuring cylinders
- Setup of eureka cans
- Rounding or significant figure errors

Question 15

What is a hazard in the density practical?

Answer 15

Water spilled from the eureka can.

Question 16

What is the consequence of water spilling?

Answer 16

A person could slip and fall.

Question 17

What is the control measure for spilled water?

Answer 17

Use a measuring cylinder to collect displaced water carefully and prevent spills.