Candle Heat Lab
Mass of the candle was measured before proceeding to further steps.
100 mL of chilled water, which is 10-15 ºC colder than the room temperature, was prepared and was poured into the empty can.
An apparatus was installed with a stand and a holder. The can was placed hanging on the stand by a glass rod (the rod went through the hole of can’s handle (?) and was placed above the holder). The candle was installed right below (about 2cm below) the can.
The room temperature and the water temperature were measured to the nearest 0.1 ºC and was recorded.
Light the candle, and stir with the other glass rod that was prepared. Usage of thermometer to stir the water was avoided.
When the candle becomes shorter, bring the can holder lower, closer to the candle fire.
The water was …show more content…
Calculations/Analysis Through this lab, we are now able to calculate the molar heat of combustion for paraffin, since we have the difference of the mass in candle before/after and the periodic table of elements (for converting g to moles of paraffin). Molar heat of combustion = (kJ of heat)/(mole of fuel) However, we do not know how much heat was released nor the mole of fuel (paraffin). In order to find the amount of heat released, we use the formula: g=mcΔT. Here, g represents the heat, m represents the mass of water, ΔT represents the change in temperature, and c represents the specific heat capacity of the water. Since the volume of the water was 100 mL and 1 mL=1g, we can substitute m=100g. ΔT would be 25 ºC, and the c would be 4.184 J/(g)(ºC). g=(25)(4.184)(100)=10460 J (11000 J with sig figs) To find the mole of paraffin, dimensional analysis is used.
(0.4g paraffin)(1 mol paraffin/352 g paraffin)=0.00113666… mol paraffin Finally, in order to calculate the molar heat of combustion:
10460 J/0.00113666..mol paraffin: 9204800 J/mol = 920.480 kJ/mol, (9.2)(102) kJ/mol with sig
100 mL of chilled water, which is 10-15 ºC colder than the room temperature, was prepared and was poured into the empty can.
An apparatus was installed with a stand and a holder. The can was placed hanging on the stand by a glass rod (the rod went through the hole of can’s handle (?) and was placed above the holder). The candle was installed right below (about 2cm below) the can.
The room temperature and the water temperature were measured to the nearest 0.1 ºC and was recorded.
Light the candle, and stir with the other glass rod that was prepared. Usage of thermometer to stir the water was avoided.
When the candle becomes shorter, bring the can holder lower, closer to the candle fire.
The water was …show more content…
Calculations/Analysis Through this lab, we are now able to calculate the molar heat of combustion for paraffin, since we have the difference of the mass in candle before/after and the periodic table of elements (for converting g to moles of paraffin). Molar heat of combustion = (kJ of heat)/(mole of fuel) However, we do not know how much heat was released nor the mole of fuel (paraffin). In order to find the amount of heat released, we use the formula: g=mcΔT. Here, g represents the heat, m represents the mass of water, ΔT represents the change in temperature, and c represents the specific heat capacity of the water. Since the volume of the water was 100 mL and 1 mL=1g, we can substitute m=100g. ΔT would be 25 ºC, and the c would be 4.184 J/(g)(ºC). g=(25)(4.184)(100)=10460 J (11000 J with sig figs) To find the mole of paraffin, dimensional analysis is used.
(0.4g paraffin)(1 mol paraffin/352 g paraffin)=0.00113666… mol paraffin Finally, in order to calculate the molar heat of combustion:
10460 J/0.00113666..mol paraffin: 9204800 J/mol = 920.480 kJ/mol, (9.2)(102) kJ/mol with sig