Them Six Markers

Seite 1

1. Describe and explain the processes in which heat is transferred from a hot cooker to a potato in a pan of water

- Conduction from the cooker to the pan

- Conduction through the pan

- Conduction from the pan to the water

- Convection from the water to the potato

- Convection through the water

MAX 2 marks

Convection

- The water is heated causing hit particles to gain energy and spread out (2)

- This causes the fluid to become less dense and expand and rise. (3)

MAX 4 marks

Conduction

- Free electrons gain kinetic energy, moving faster and diffuse through the metal

MAX 2 marks

2. State and explain what happens to the temperature of a bowl of water as it evaporates (5)

- The temperature of water will decrease.

- There are attractive forces between molecules

- Only the fastest molecules have enough energy to break away from other molecules

- Therefore the average energy of the remaining molecules goes down

- The lower the speed of the molecules the lower the temperature

3. Explain how a vacuum flask is designed to reduce heat loss

-The vacuum between the two walls of the container cuts out energy transfer by conduction and convection between the walls.

-Glass is a poor conductor so there is little energy transfer by conduction through the glass

-The glass surfaces are silvery to reduce radiation from the outer wall

- The spring supporting the double walled container is made of plastic which is a good insulator

- The plastic caps stops cooling by evaporation. Conduction is also deuced as plastic is a poor conductor.

4. Compare the similarities and differences between the process of conduction in metals and non-metals

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