Candle Experiment PDF

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Lab assignment for the candle experiment....

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Candle Experiment By: Megan Tchaderjian #3349339 2017-11-06 Purpose: To observe several ways of extinguishing a flame and how a flame can affect its surroundings. The following experiments incorporated the use of a candle; when burning a candle, the wax melts and rises through capillary action into the wick where it oxidizes and enters the air as vapour. This process can be defined by the following chemical reaction: Wax + O2  H2O (g) + CO2 (g) + heat + light Procedure: The experiments were carried out as described in Candle Experiment of the Chemistry 217 Home Laboratory Manual, pp. 54-55. No changes or modifications were made. Observations: Part A. Re-igniting a Candle:

1. 2. 3.

Candle is lit (1minute) Candle flame is blown out, smoke trail is created at tip of wick

New flame put into the smoke trail, re-ignites flame on candle Part B. Water Suck Up: 1. Candle is lit 2. Water remain still 3. Flame burns out 4. Water rises Part C. Extinguishing a Candle with Aluminum Foil: 1. Candle is lit 2. Place aluminum around wick, flame grew in size 3. Flame burned out Part D. Candle Condensation: 1. Candle is lit 2. Place ice pack above flame 3. Bottom end of aluminum foil gets wet, forming water droplets Part E. Extinguishing a Candle with Carbon Dioxide: 1. Candle is lit 2. Combine baking soda and vinegar, creates fizz and foamy mixture 3. Slightly tilt jar toward flame, flame immediately extinguishes Results:

Part A. Re-igniting a Candle: 1. When wick is lit, the flame vaporizes the candle wax and it turns into heat + light 2. When flame is blown out, the smoke trail contains wax that was never burned, therefore new flame ignites this unburned wax Part B. Water Suck Up: 1. Candle flame heats the air, causing the surrounding air to expand 2. This air expansion temporarily cancels out the depletion of oxygen.

3. Eventually the oxygen depletion overcomes and extinguishes the flame 4. Air cools, causing air to decrease in volume which causes water to rise Part C. Extinguishing a Candle with Aluminum Foil: 1. Foil around wick prevents oxygen from getting to the candle wax 2. Flame increases carbon dioxide levels and decreases oxygen levels 3. Hot air briefly causes a convection current which carries oxygen to the flame, thus its increase in size) just before all the oxygen is consumed 4. Oxygen consumption = flame extinguishes Part D. Candle Condensation: 1. Warm air rises and cools as it reaches cooler temperatures, created by ice pack 2. Air condenses and forms water droplets Part E. Extinguishing a Candle with Carbon Dioxide: 1. When one mixes baking soda and vinegar, carbon dioxide is released in the process 2. Simply tilting the jar towards the flame guides the built up carbon dioxide towards the flame, and flame extinguishes Answers to questions: 1. Why did the candle reignite with a match held away from the wick? As stated in the results/explanation section, the smoke trail left behind by the burned out f lame contained wax that had never burned. Therefore, when a new flame was introduced into the smoke trail, the unburned wax caught on fire. This trail lead back to the wick, where one can observe a reignited flame. 2. a. Explain how the candle was extinguished with aluminum foil and carbon dioxide. In this experiment, we are observing how a candle flame requires oxygen and wax to burn. By placing an aluminum foil between the wax and the flame, oxygen is not able to reach the candle to fuel the flame. Meanwhile, carbon dioxide is released and with lack of oxygen to fuel the flame, the flame eventually burns out. b. Suggest and explain another method to extinguish a candle not already used in Part A of this experiment. Covering a lit candle with a jar will extinguish the flame. The candle flame burns through all the oxygen in its surrounding (in the jar), and since oxygen is a fuel, once it runs out, the flame will burn out as well. c. Write out the balanced chemical equation for the reaction that produced the carbon dioxide you used to extinguish the flame. CaCO3 (s) + 2HCl (aq)  CaCl2 (aq) + H2O (l) + CO2 (g)

3. What does the formation of water on the aluminum ice sack suggest about the chemistry of a burning candle? Candles are hydrocarbons, compounds made up of hydrogen and water. Anytime a hydrocarbon undergoes combustion, the products are water and carbon dioxide. That being said, when a candle burns, some water is formed which condenses to liquid when t he hot water vapor comes into contact with the cooled aluminum sack. 4. a. Suggest a reason why the water is sucked up into the glass jar One reason why the water may have been sucked up into the jar is with the depletion of oxygen. However, if this were the only reason, the water would have raised so subtly it almost wouldn’t have even been noticeable. b. A candle flame will use up oxygen as it burns. However, the consumption of oxygen alone does not explain the observed volume change. What other factor(s) need to be considered? At first, the flame heats the air inside the jar and this hot air expands quickly. When the flame fades and goes out, the air in the jar cools. Cooler air takes up less space. That decrease in volume creates lower pressure in the jar. The higher pressure outside the jar pushes the water into the jar. The water stops rising when the pressure inside and outside the jar reaches equilibrium. 5. Explain the difference in the shapes of the two flames (Normal candle and the nearly identical candle in micro gravity flame) shown on p 51 of this manual.

rises

Flames we are used to seeing here on Earth expand when in need of more fuel (i.e. oxygen). The teardrop shape that flames morph into are caused by gravity; hot air and draws cool air behind it. However, up in space where oxygen is limited, the flame “balls up” and lets the oxygen come to it. Dr. William, a physics professor at UC San Diego, reports that normal flames produce soot, carbon dioxide and water, whereas these flames up in space produce carbon monoxide and formaldehyde. These flames do not burn for long on Earth but can last for many minutes under low gravity conditions. According to Williams, these are interesting findings that can guide future research and lead to cleaner auto-ignitions. https://science.nasa.gov/science-news/science-at-nasa/2013/18jun_strangeflames...