Extra question P6

Question 1

Describe how the student could use joulemeter, electric heater, beaker, top pan balance and thermometer to determine the specific heat capacity of vegetable oil.

Answer 1

*   measure mass of oil using the top pan balance
*   measure start temperature of oil using the thermometer
*   place beaker of oil on heater
*   switch on heater to heat oil
*   measure final temperature of oil using the thermometer
*   measure energy transferred using joulemeter
*   calculate increase in temperature (Δθ)
*   use the equation E = mcΔθ to determine c

Question 2

As the temperature of the air decreased from 20 °C to –190 °C the argon changed from a gas to a liquid to a solid.
Explain the changes in the arrangement and movement of the particles of the argon as the temperature of the air decreased.

Answer 2

cooling
*   as the argon cools the particles slow down

gas to liquid
*   particles change from being spread apart to touching each other

liquid to solid
*   particles change from a random arrangement to a regular pattern
*   particles change from moving freely to fixed positions
*   (internal) energy (of the argon) decreases
*   attractive forces between particles are stronger in a solid than in a liquid

Question 3

How does conduction work

Answer 3

atoms gain (kinetic) energy
atoms collide with neighbouring atoms
transferring energy to (neighbouring / other) atoms
making atoms vibrate with bigger amplitude

Question 4

Describe solids particles

Answer 4

• arranged in a regular pattern
• particles vibrate about fixed points
• particles have low energy.

Question 5

Describe liquids particles

Answer 5

• pattern is irregular
• particles are not fixed in place or can move freely / around
• particles have more energy than solids and / or less energy than gases.

Question 6

describe gas particles

Answer 6

• particles are in a random pattern
• particles move (about) freely / randomly
• particles have high energy.

Question 7

Explain why the iceberg will melt.

Answer 7

the internal energy of the iceberg increases because energy is transferred from the water to the ice

Question 8

Explain, in terms of the particles in a liquid, why evaporation causes cooling.

Answer 8

changing state from solid to liquid / melting
at steady temperature
temperature of liquid rises until it reaches boiling point

Question 9

Explain why the different thermal conductivities of metal and plastic are important in the design of the bowl.

Answer 9

metal: has a high thermal conductivity
which increases the rate of energy transfer from the mixture
plastic: has a low thermal conductivity
which reduces the rate of energy transfer from the surroundings

Question 10

Explain why a mass of gaseous water at 100 °C contains more energy than an equal mass of liquid water at 100 °C.

Answer 10

energy is needed to change the state of the water to break the bonds

Question 11

Water and the chemical isooctane both boil at 100 oC. When the same amount of each substance is placed on a heater, the isooctane boils first. Explain why this happens.

Answer 11

• lower specific heat capacity than water
• less energy is needed to raise its temperature to its boiling point.

Question 12

Whats a chemical change

Answer 12

New substance is formed

Question 13

The liquid coolant has a freezing point below –20 °C
Explain one other property that the liquid coolant should have.

Answer 13

a high specific heat capacity so it can absorb a large amount of energy with only a small temperature change

Question 14

Explain why liquids are more energetic than solids

Answer 14

The particles have more kinetic energy, because they are moving faster, and more potential energy because they are slightly further apart

Question 15

Explain why the densities of a solid and Liquid Metal are similar

Answer 15

• in both arrangements, particles are touching
• density is the mass per unit volume: for a given mass, the volumes will be similar and so will the densities

Question 16

For a given substance, the specific latent heat of vaporisation is higher than the specific latent heat of fusion. Explain why

Answer 16

• when you heat a substance and it changes state, you increase the potential energy but not the kinetic energy
• this requires more energy per kilogram for a liquid to gas than for a solid to liquid because you are completely breaking the bonds between the particles

Question 17

The specific heat capacity of ice is less than the specific heat capacity of water. Explain how the figure above shows this.

Answer 17

• the gradient for ice is steeper than the gradient for water
• this means that less energy is needed to increase the temperature by a fixed amount

Question 18

A second student did the same investigation and recorded the temperature until the water
produced boiled.
In the second student’s investigation more thermal energy was transferred to the
surroundings.
Describe two ways the results of the experiment in the figure above would have been
different.

Answer 18

• it would take more time for the water to change state
• the water’s temperature would increase more slowly

Question 19

The student only measured the volume of each fruit once.
The volume measurements cannot be used to show that the method to measure volume
gives precise readings.
Give the reason why

Answer 19

Repeat readings of volume should be taken to show that the readings are close together

Question 20

Do gas particles move at the same or a rage of speeds

Answer 20

A range of speeds

Question 21

Give two advantages of using dataloggers and temperature probes compared to using the
thermometer

Answer 21

takes readings automatically
higher resolution

Question 22

The temperature of the helium in the balloon was increased.
The mass and volume of helium in the balloon remained constant.
Explain why the pressure exerted by the helium inside the balloon would increase.

Answer 22

• particles would have a higher (mean) kinetic energy
• so increased number of collisions with the walls of the balloon per second
• greater forces exerted in collisions (between particles and balloon walls
• greater force exerted on same area

Question 23

The mass of the metal cube was measured using a top pan balance.
The balance had a zero error.
Explain how the zero error may be corrected after readings had been taken from the
balance.

Answer 23

• record the zero error when there is no object on the balance
• subtract/add the value of the zero error

Question 24

A student measured the mass of boiling water that was turned into steam in five minutes.
Explain how the student could use this information to estimate the power output of the
Bunsen burner in watts