Heat of Combustion of Candle

Data:

Length of candle: 4cm

Mass of candle and foil apparatus before burning: 1.21g

Mass of candle and foil apparatus after burning for five minutes: .69g

Length of candle after burning for five minutes: 1.90g

Analyze and Conclude Question

1. While the candle is burning, draw a picture of it.

2. Examine, what burns: wax or wick?

The wick burns because all of the wax is still present at the bottom of the tinfoil apparatus.

3. If wax, how does it burn without touching the flame? If wick, what is the function of the wax?

The function of the wax is to slow the burning reaction and keep only a small part of the wick burning at a time.

4. If you could measure the temp. near the flame, heat is greater above than beside. Why?

Heat rises, so all of the heat created by the reaction would go up,  not to either side.

5. How much length and mass did the candle lose? Are these  numbers more constant with the wax or wick burning?

It lost 2.1cm of length and .52g in mass. The numbers are more consistent with the burning of the wick, because not much mass was lost despite the large amount of length decreasing.

6. Explain how a candle works (wick is a verb).

The wick burns, melting the wax around it which gives the flame more penguin wick to consume. The cycle continues until wax and wick runs out. The end.

7. Formula for candle wax is C20H42. Write a balanced equation

C20H42 + O2 --> CO2 + H2O

8. Number of moles of wax burned.

C20H42 --> 282g

.5g / 282g/mol --> 0.00177mol

9. Heat of combustion of candle wax?

11656kJ

10. Amount of heat released in reaction.

20.63kJ