Download How to calculate the Heat / Molar Heat of Combustion

How to calculate the Heat / Molar Heat of Combustion of a Hydrocarbon
Name_____________________________________
A student performed the heat of combustion lab and collected the following data:
Volume of water in the can: 93.8 mL
Initial temp of the water in the can: 23oC
Final temp of the water in the can: 35oC
Initial mass of the candle: 9.57 g
Final mass of the candle: 9.02 g
a. What is the mass (in grams) of the water in the can? ______________________________
b. Calculate the total rise in temperature of the water. Show your work below.
___________________
c. If the specific heat capacity of water is 4.184 J/g.oC, what is the amount of heat energy, in kilojoules, that was
absorbed by the water?
Step 1: Write the equation to calculate q:
Step 2: Substitute your data into the equation and calculate:
_______________________
Step 3: Convert Joules to kilojoules:
Show your work:
_______________________
d. Determine the amount of energy, kJ, released by the candle:
_______________________
e. Calculate the mass of the candle that burned.
Show your work:
_______________________
f. Calculate the heat of combustion of the candle, in kJ/g.
Show your work.
_______________________
Energy released by the candle
=
Mass of the candle burned
Cont. on back side…
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g. State the name of the law that we assume is obeyed in this system.
h. Calculate the molar heat of combustion, in kJ/mol, of the candle.
Step 1: Suppose the formula for the candle wax is C30H62. Calculate the molar mass of the wax:
Show your work.
Step 2: Calculate the moles of candle that burned:
Show your work.
Step 3: Calculate the energy released per mole, kJ/mol, of candle:
Energy released by the candle
=
Moles of the candle burned
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i. The molar heat of combustion of the candle = _____________________________
j. Write the thermochemical formula for the combustion of C30H62: