Candle Chem Lab

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  • Topic: Hydrocarbon, Candle, Hydrogen
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  • Published : April 8, 2013
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Chemistry Chapter 4
The Candle Lab|
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Before You Start –
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The scientific process is a systematic way of explaining how events are related to each other in the natural world. Careful observations are the first step in this process. An observation is a fact obtained with the senses. -------------------------------------------------

You might think that a burning candle is pretty simple. But, if you really look at it, a burning candle turns out to be a rather complex process. -------------------------------------------------
During this lab investigation, you will observe a burning candle, formulate questions about the process, and conduct experiments to gain insight into what is happening. What you find may surprise you! -------------------------------------------------

Background on Candles to Help You Get Thinking
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A candle is made of paraffin (also known as paraffin wax (C25H52)), and a wick of cotton (C6H10O5). Paraffin is purified from crude oil, and is thus a petroleum product. Petroleum is formed in the Earth in a natural process over the period of millions of years. Paraffin is a mixture of molecules made of carbon and hydrogen. The hydrogen and carbon composition of paraffin is the reason it is classified as a hydrocarbon. Although paraffin is comprised of a variety of different molecules, a typical molecule contains 25 carbon atoms, and 52 hydrogen atoms; we can use this to give us C25H52 as a rough chemical formula for paraffin. Paraffin, like other products from crude oil such as gasoline, diesel, and kerosene, is a hydrocarbon fuel. The burning of any hydrocarbon produces carbon dioxide (CO2), water (H2O), and heat. -------------------------------------------------

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The wick in a candle is typically a braided cotton string. Cotton consists largely of cellulose. Cellulose is the most abundant biomolecule on Earth. It is composed of six carbon (C), ten hydrogen (H), and five oxygen (O) atoms.

Materials Required
* 250mL Beaker and/or 500mL Erlenmeyer flask
* metric ruler
* balance
* matches
* a small candle
* aluminum foil
* Ceramic Plate
* Goggles

Theory
In burning a candle one starts with a solid fuel (wax), which is liquefied, rising up into the wick by capillary action to be vaporized in the atmosphere, and then quickly oxidized by the candle flame. In burning, the candle produces energy in the form of heat and light. The burning process is a simple organic chemical reaction represented by the following equation:

If one were to remove the fuel (wax), the oxygen or the initiator (flame) or any combination of the three, the candle would go out. Professional fire-fighters use this idea constantly when they develop strategies for fighting fires.

Figure CE.1
Candle flame
Figure CE.1 shows a detailed diagram of the flame of a burning candle and will give you a better idea of the mechanics involved.

I. Observing an Unlit and a Lit Candle
Procedure
1. Light the candle, drip enough wax onto the center bottom of the fingerbowl to attach the candle.
2. Observe the candle accurately and precisely. Use your senses: sight, sound, feel, smell (but not taste!). Record at least 5 precise observations in your lab notebook under the heading "OBSERVATIONS, BEFORE BURNING."

3. Light the candle. Observe the candle and flame as carefully as you can. Record at least 5 observations in your lab notebook under the heading "OBSERVATIONS, DURING BURNING." Include a fully labeled color sketch with a scale for sizing. (Observe the candle burning for at least two (2) minutes.)

4. Blow the candle out. Observe the candle until no more changes are taking place. Record at least 5 precise and accurate observations under the heading "OBSERVATIONS, AFTER EXTINGUISHING."...
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