Paper 1 Required Practicals

Question 1

Required Practical 5: Determining Density Apparatus and resolution?

Answer 1

• Resolution of measuring equipment:
  
  • 30 cm ruler = 1 mm
  • Vernier calipers = 0.01 mm
  • Micrometer = 0.001 mm
  • Digital balance = 0.01 g

Question 2

3.1.3 Required Practical: Determining Density for regular object

Aim, Variables and Methods

Answer 2

• The aim of this experiment is to determine the densities of regular objects by using measurements of their dimensions

Variables:

• Independent variable = Type of shape / volume
• Dependent variable = Mass of the object

1. Place the object on a digital balance and note down its mass
2. Use either the ruler, Vernier calipers or micrometer to measure the object’s dimensions (width, height, length, radius) – the apparatus will depend on the size of the object
3. Repeat these measurements and take an average of these readings before calculating the density

Question 3

3.1.3 Required Practical: Determining Density for regular object

Results

Answer 3

• Calculate the volume of the object depending on whether it is a cube, sphere, cylinder (or other regular shape)
• Remember to convert from centimetres (cm) to metres (m) by dividing by 100

1 cm = 0.01 m

50 cm = 0.5 m

• Using the mass and volume, the density of each can be calculated using the equation:

p = m/v

• Where:
  
  • ρ = density in kilogram per metres cubed (kg/m³)
  • m = mass in kilograms (kg)
  • V = volume in metres cubed (m³)

Question 4

3.1.3 Required Practical: Determining Density for Irregularly-Shaped object

Answer 4

• The aim of this experiment is to determine the densities of irregular objects using a displacement technique

Variables:

• Independent variable = Different irregular shapes / mass
• Dependent variable = Volume of displaced water

Method:

1. Place the object on a digital balance and note down its mass
2. Fill the eureka can with water up to a point just below the spout
3. Place an empty measuring cylinder below its spout
4. Carefully lower the object into the eureka can
5. Measure the volume of the displaced water in the measuring cylinder
6. Repeat these measurements and take an average before calculating the density

• The volume of the water displaced is equal to the volume of the object
• Once the mass and volume of the shape are known, the density can be calculated using:

p = m/v

Question 5

3.1.3 Required Practical: Determining Density for Liquids

Answer 5

• The aim of this experiment is to determine the density of a liquid by finding a difference in its mass

Variables:

• Independent variable = Volume of water added
• Dependent variable = Mass of cylinder

Method:

1. Place an empty measuring cylinder on a digital balance and note down the mass
2. Fill the cylinder with the liquid and note down the volume
3. Note down the new reading on the digital balance
4. Repeat these measurements and take an average before calculating the density

Analysis of Results

• Find the mass of the liquid by subtracting the final reading from the original reading

Mass of liquid = Mass of cylinder with water – mass of cylinder

• Remember to convert between grams (g) and kilograms (kg) by dividing by 1000

1 g = 0.001 kg

78 g = 0.078 kg

• Once the mass and volume of the liquid are known, the density can be calculated using the equation:

p = m/v

Question 6

3.1.3 Required Practical: Determining Density

Errors and Safety considerations

Answer 6

Systematic Errors:

• Ensure the digital balance is set to zero before taking measurements of mass
  
  • This includes when measuring the density of the liquid – remove the measuring cylinder and zero the balance before adding the liquid

Random Errors:

• A main cause of error in this experiment is in the measurements of length
  
  • Ensure to take repeat readings and calculate an average to keep this error to a minimum
• Place the irregular object in the displacement can carefully, as dropping it from a height might cause water to splash which will lead to an incorrect volume reading

Safety Considerations

• There is a lot of glassware in this experiment, ensure this is handled carefully
• Water should not be poured into the measuring cylinder when it is on the electric balance
  
  • This could lead to electric shock
• Make sure to stand up during the whole experiment, to react quickly to any spills

Question 7

Required Practical 2: Investigating Insulation

Aims and Variables

Answer 7

Aim of the Experiment

• The aim is to investigate the effectiveness of different materials as thermal insulators and the factors that may affect the thermal insulation properties of a material
• This is the only one way this experiment could be carried out
• Resolution of measuring equipment:
  
  • Thermometer = 1 °C
  • Stopwatch = 0.01 s

Question 8

Required Practical 2: Investigating Insulation

Method and Results

Answer 8

1. Set up the apparatus by placing a small beaker inside the larger beaker
2. Fill the small beaker with boiling water from a kettle
3. Place a piece of cardboard over the beakers as a lid. It should have a hole suitable for a thermometer and place the thermometer through this hole and into the water in the small beaker
4. Record the temperature of the water in the small beaker and start the stopwatch
5. Record the temperature of the water every 2 minutes for 20 minutes, or until the water reaches room temperature
6. Repeat the experiment, each time changing the cardboard for another insulating material (in any order) and also without any insulation at all

Question 9

Required Practical 2: Investigating Insulation

Results

Answer 9

• Plot a graph of temperature against time and draw a curve of best fit
  
  • Plot all the curves for each material on the same axis
• The graphs should show that the temperature falls quickly at high temperature, then more slowly (shown by the graph levelling out)
  
  • When the water is at a high temperature, there is a greater temperature difference between it and room temperature. This creates a high rate of energy transfer
  • When the water is at a low temperature, there is less temperature difference between it and room temperature. This creates a low rate of energy transfer
• The curve which takes the longest time for the temperature to drop is the shallowest
  
  • This material is the best insulator

An example graph might look like this

Question 10

Required Practical 2: Investigating Insulation

Safety Considerations and Errors

Answer 10

Evaluating the Experiment

Systematic Errors:

• Make sure the starting temperature of the water is the same for each material since this will cool very quickly
  
  • It is best to do this experiment in pairs to coordinate starting the stopwatch and immersing the thermometer
• Only the top of the beaker is covered, so heat escapes through the sides of the beaker, an alteration of this experiment could be:
  
  • Putting the insulating materials around the beaker as well as on top of it
  • Using one material with different thicknesses. This will show that the thicker the material, the better the insulation
• Use a data logger connected to a digital thermometer to get more accurate readings

Random Errors:

• Make sure the hole for the thermometer isn’t too big, otherwise the heat will escape through the hole
• Take repeated readings for each insulator
• Read the values on the thermometer at eye level, to avoid parallax error

Safety Considerations

• Keep water away from all electrical equipment
• Make sure not to touch the hot water directly
  
  • Run any burns immediately under cold running water for at least 5 minutes
• Do not overfill the kettle
• Place the small beaker inside the large beaker first before pouring water in, since the small beaker will become very hot
• Make sure all the equipment is in the middle of the desk, and not at the end to avoid knocking over the beakers
• Carry out the experiment only whilst standing, in order to react quickly to any spills