2C.3 LAB: DETERMINING THE NUMBER OF MOLES AND MOLECULES USED UP IN A BURNING CANDLE

PURPOSEto burn candle wax and to determine the number of moles and molecules used up

PROCEDURE

1) Mass a glass plate _______________grams
2) Light a candle. drip a little of wax on the plate. stick candle to plate
blow out candle. find the total mass ______________grams
calculate the mass of the candle by itself _________ grams
3) Light the candle and allow it to burn 3 minutes. do not play with wax
this will effect your results. blow out candle
4) Reweigh the candle and plate without losing any melted wax __________gram
calculate the new mass of the candle by itself _________grams
5) Calculate the mass of the candle that burned in 3 minutes________grams

CALCULATIONS

Wax is a mixture of hydrocarbons. C₂₅H₅₂ can be used as a representative hydrocarbon in the mixure. The burning of wax is shown below:

C₂₅H₅₂ + _____ O₂ -------> ______CO₂ + ______H₂O + energy

a) Balance the equation. Count atoms below.

___________ carbon ___________
___________hydrogen___________
____________oxygen____________
b) What is the molar mass of wax?






c) How many moles of wax were in the candle before it burned ?






d) How many molecules are in the candle before it burned?





e) How many moles of wax were used up during the burning?






f)How many molecules were used up during the burning?





g) How long would it take to burn 1 mole of candle?

CONCLUSIONS

1) What 2 resources are used up as a candle burns?


2) What has happened to the atoms in these resources?




3) Is it possible to recover these 2 resources after they've been used? Explain