Wednesday, June 11, 2014
Monday, June 2, 2014
Sunday, June 1, 2014
Thursday, May 29, 2014
Tuesday, May 27, 2014
Monday, May 19, 2014
Tuesday, May 13, 2014
Thursday, May 1, 2014
Wednesday, April 30, 2014
Thursday, April 24, 2014
Tuesday, April 22, 2014
Friday, April 18, 2014
Thursday, April 17, 2014
Friday, April 11, 2014
Thursday, April 10, 2014
Tuesday, April 8, 2014
Monday, April 7, 2014
Heat of Combustion of a Candle Lab
Purpose:
To observe a burning candle and calculate the heat associated with the combustion reaction.
Procedure:
1) Measure and record the length of a candle in centimeters.
2) Place the candle on a small piece of aluminum foil and measure the mass of the foil-candle system.
3) Note the time as you light the candle. Let the candle burn for about five minutes.
4) Extinguish the candle and record the time.
5) Measure the mass of the foil-candle system again.
Data:
Analyze and Conclude:
2) The wick is the one that is burning.
3) The wax is there to hold the wick in place.
4) The air on top of the candle is hotter because heat rises.
5) The candle lost 1.2 centimeters and lost .3 grams. For length it would be mostly the wax and for mass it would be the wick.
6) The wick acts as towel and soaks up the wax. Then the wax and wick burn.
7) C20 H42 30 1/2 O2 ---> 20CO2 + 21H2O
8) 1.16g (1mol/282g) = .00411348 mol
Thursday, April 3, 2014
Tuesday, April 1, 2014
Heat of Fusion Lab
Purpose:
Determine the heat of fusion.
Procedure:
1) Start with 100 ml H2O at 50° C
2) Place into calorimeter (cup). Record temperature.
3) Drop 2 to 3 ice cubes in. Stir don't run out of ice.
4) Once temperature stabilizes around 0° C. Remove ice.
5) Measure new volume.
Data Table:
Calculations:
1) Mass of 100 ml H2O = 100g
2) Cal q= M x ^T x C
q= 80g x 50° C x 4.18 KJ/mol
3) Determine q= 16,720 KJ
4) Mass of ice melted = 80g H2O
5) Mole of ice melted= 4.4 mole H2O
6) ^H fusion for ice = KJ/mol
16,720/1000= 16.72 KJ/4.4 mole= 3.8 KJ/mol
Conclusion:
^H= 6.01 KJ/mol
^H= 3.8 KJ/mol
Percent error: 36.7 percent off of the theoretical yield
We had a lot of errors in our experiment the causes a large percent error. Some errors included waiting too long to put the ice cubes in so it was not at 100° C when we started. That means we did not need as much ice cubes. This caused a difference from the theoretical yield.
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