P1 Materials - Determine the densities of a variety of objects both solid and liquid

Question 1

Aim

Answer 1

To measure the density of various materials

Question 2

Method 1: Regular solids

Answer 2

1. Place the cuboid on the top pan balance and record its mass in grams
2. Use a ruler to measure the length (l), width (w) and height (h) of a cuboid
3. Calculate the volume of the cuboid using:
   Volume = l x w x h
   (where measurements are in cm and the volume is in cm3)
4. Use the measurements from steps 1 and 3 to calculate the density of the substance

Question 3

Method 2: Stone or other irregular shaped object

Answer 3

1. Place the object on the top pan balance and record its mass in grams
2. Fill the displacement can until the water is level with the bottom of the pipe
3. Place a measuring cylinder under the pipe, ready to collect the displaced water
4. Carefully drop the object into the can and wait until no more water runs into the cylinder
5. Measure the volume of the displaced water
6. Use the measurements from steps 1 and 5 to calculate the density of the object

Question 4

Method 3: Water (or any liquid)

Answer 4

1. Place an empty measuring cylinder on the top pan balance and measure its mass in grams
2. Pour 50 cm3 of liquid into the measuring cylinder and measure its new mass
3. Calculate: mass of liquid = (mass at step 2) - (mass at step 1)
4. Use the volume (50 cm3) and the answer to step 3 to calculate the density of the liquid

Question 5

Results:

Record the results in a suitable table. The one below gives some example measurements.

Answer 5

.

Question 6

Analysis:

Calculate the densities of the different substances using:

density = ?

Convert the densities to _/_3:

Answer 6

density = mass ÷ volume

density of steel = 468/60 = 7.8 g/cm3
density of stone = 357/68 = 5.25 g/cm3
density of water = 50/50 = 1.0 g/cm3

Convert the densities to kg/m3:

density of steel = 7.8 × 1,000 = 7,800 kg/m3
density of stone = 5.25 × 1,000 = 5,250 kg/m3
density of water = 1.0 × 1,000 = 1,000 kg/m3

Question 7

Evaluation 1
- source of error with measuring mass + improvement

Answer 7

The top pan balance is only precise to ±1 g. A balance that reads to 1 decimal place (±0.1 g) or to 2 decimal places (±0.01 g) would be more precise.

Question 8

Evaluation 2
- displacement source of error + improvement

Answer 8

The displacement can may not have been set up correctly each time, so another added drop of water would cause some to dribble out of the spout before use. Check that no more water comes out before placing the measuring cylinder under the spout.

Question 9

Hazard, consequence, control - displacement

Answer 9

Hazard = Water spilled from displacement can

Consequence = Slip and fall

Control measures = Work next to a sink and have paper towels ready to mop up any spills

Question 10

There are different ways to investigate density. In this practical activity, it is important to:

(Meant to be card 1)

Answer 10

use appropriate apparatus and methods to measure volume and mass

make accurate measurements of the mass and the volume of different objects, and use these measurements to calculate densities