UNIT 3- FUELS

1. What is a fuel and give some examples

2. What is the chemical reaction that takes place and what is the equation?

1. A fuel is a substance that releases heat energy when it is burned. For example, petrol and gas.

2. Combustion - Fuel + Oxygen = Carbon Dioxide + Water

1. What is needed to break bonds and what is released when bonds are made?

2. What fuels may be burned in a spirit burner?

1. Energy

2. Liquid fuels such as petrol + paraffin

Investigate how much energy food contains

1. Measure 10cm3 of water using a measuring cylinder and add it to a boiling tube- attach the beaker to a clamp stand with a clamp and boss

2. Read and record starting temp of water using a thermometer

3. Measure the mass of the food sample using a mass balance

4. Fix the food onto the needle with the wooden holder and ignite the food using a Bunsen burner

5. Place it under the boiling tube until it stops burning & record the highest temp reached by the water

6. Calculate the temp change by doing final temp - initial temp

7. Repeat steps 1-6 3 times by changing the type of food each time & calculate a mean

Hazards, risks and precautions with fuels

• Flammable - flames can spread quickly - Use heatproof mat

• Toxicity - can irritate eyes - Use safety goggles

• Risk of explosion - rapid combustion can cause spitting - fume cupboard

Investigate how much energy food contains- what are the variables from this experiment above?

IV = Type of food

DV = Temp change of water

CV = Volume of water, type of fuel used + same burning time

Investigate how the type of fuel affects the energy transferred when burned.

1. Attach copper calorimeter to clamp stand with a clamp and boss, and position ruler on the side of the stand, to measure the distance of the flame and calorimeter

2. Using a MC, measure 50cm3 of water and add it to the calorimeter with a thermometer inside to fully submerge it in

3. Measure the initial temp of the water using the thermometer and measure the mass of the Sburner using a digital balance

4. Ignite the flame and allow it to burn for 60s then extinguish the flame using the lid

5. Record the final temp of water and measure the mass of the SB

6. Change the water and repeat process 3 times, using diff alcohols (each increasing by one chain length up to 5)

7. Measure the energy by- Energy (J)= mass of water (g) x s.h.c x change in temp

8. Then calculate J/g by- Energy/mass of fuel combusted