Heat of Combustion Candle Wax Calorimetry

In summary, the task is to find the heat of combustion for candle wax using a simple calorimeter. However, the lab books do not provide specific information on the calorimeter's specific heat or a formula for heat of combustion. The data collected includes a final temperature of 42.0 degrees Celsius, a mass of 97.00g for the wax (after melting with base), and 1850 cal/g degrees Celsius absorbed by the can. The mass of water is 50g and the mass of the wax is 0.20g. The candle wax formula is C36H74. The necessary information to calculate the heat of combustion is the mass of water, specific heat capacity of water, and temperature change. It is
  • #1
Lancer232
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Homework Statement


I'm supposed to find the heat of combustion for candle wax (which was used to boil water in a simple calorimeter), yet I have no clue on how to do it, the lab books at school do not tell anything about the calorimeter's specific heat or give a formula for heat of combustion. So far I have my final temperature at 42.0 degrees Celsius, mass of 97.00g (after melting, with base), 1850 cal/g degrees Celsius absorbed by the can (formula used was Cal=mass H2O X Temperature Change H2O X Specific Heat of Water). My mass of H2O was 50g (assuming 1 ml is 1g, unless I got that backwards and its 1mg, I never really understood a few parts of the lab). The mass of my wax is 0.20g (97.20g - 97.00g).

Homework Equations



All I know is the candle wax's formula, C36H74
We aren't allowed to take the lab books home, and my data table is brief and straight to the point, the way my teacher wants it to be. I could figure it out on my own if I just get the formula, unless I forget something.
 
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  • #2
First you need to know how much energy you got from the candle.
For that you need the mass of water (yes 1g=1cc) the specific heat capacity of water and the temperature change (we will ignore the container)

Be careful of the units - it's probably best to convert everything in kg and J.
You have the specific heat slightly confused. Water has a specific heat capcity of around 4200J/kg/degree or 1cal/g/degree

then you can quote the heat of combustion for the candle either in J/kg or since you are given the formula you could work out how many moles and give it as J/mol.
 
  • #3


I understand your frustration and confusion with the lack of information provided in your lab books. However, I can provide some guidance on how to calculate the heat of combustion for candle wax using the information you have.

First, it is important to note that the heat of combustion is the amount of energy released when a substance is completely burned in oxygen. In this case, the candle wax is the substance and the oxygen is present in the air. The formula for calculating the heat of combustion is as follows:

Heat of combustion = (mass of water x specific heat of water x change in temperature of water) / mass of wax

Based on the information you provided, the mass of water (50g) and the change in temperature (42.0 degrees Celsius) are correct. However, the specific heat of water is not 1850 cal/g degrees Celsius. It is actually 1 cal/g degrees Celsius, which is the standard specific heat of water. This is likely a typo in your data table.

Using the corrected specific heat of water, we can calculate the heat of combustion as follows:

Heat of combustion = (50g x 1 cal/g degrees Celsius x 42.0 degrees Celsius) / 0.20g

= 10,500 cal/g

This is the amount of energy released when 0.20g of candle wax is completely burned. However, since you used 97.00g of wax in your experiment, we need to multiply this value by 97.00g to get the total heat of combustion for the amount of wax used in your experiment.

Total heat of combustion = 10,500 cal/g x 97.00g = 1,018,500 cal

Therefore, the heat of combustion for candle wax in your experiment is approximately 1,018,500 cal. I hope this helps you in completing your homework assignment. Remember to always double check your data and equations to ensure accuracy.
 

What is the heat of combustion of candle wax?

The heat of combustion of candle wax is the amount of heat released when a unit mass of wax is burned completely in oxygen. It is typically measured in units of joules per gram (J/g) or kilojoules per gram (kJ/g).

What is the purpose of using calorimetry in measuring the heat of combustion of candle wax?

Calorimetry is used to measure the heat of combustion of candle wax because it allows for accurate and precise measurement of the heat released during the burning process. It involves measuring the change in temperature of a known amount of water surrounding the burning candle, and using this data to calculate the heat released.

What factors can affect the heat of combustion of candle wax?

The heat of combustion of candle wax can be affected by various factors such as the type of wax used, the size and shape of the candle, the amount of oxygen available for combustion, and the temperature of the surroundings. These factors can influence the efficiency of the burning process and therefore impact the amount of heat released.

How is the heat of combustion of candle wax used in everyday life?

The heat of combustion of candle wax is used in everyday life in various ways, including as a source of heat and light for candles, as a way to cook food on a camping trip, and as a means of producing energy in power plants. It is also used in industries for processes such as melting and heating.

How does the heat of combustion of candle wax compare to other fuels?

The heat of combustion of candle wax is relatively low compared to other fuels such as gasoline or natural gas. This is due to the fact that candle wax is a solid fuel and has a lower energy density compared to liquid or gaseous fuels. However, candle wax has the advantage of being easily accessible and renewable, making it a popular choice for small-scale heating and lighting purposes.

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