Chem 217 - Candle Experiment PDF

Preview

Summary

Download Chem 217 - Candle Experiment PDF

Description

Candle Experiment By:

5 2020-08-12

Purpose: To observe different methods of five ways to extinguish a flame from a candle, as well as how the flames and combustion can affect its surroundings. The following equation, which was needed for the experiment to be accomplished for a candle wick to burn, is as follows: wax + O2 → H2O (g) + CO2 (g) + heat + light Procedure: The experiment was carried out as described in the Candle Experiment of the Chemistry 217 Laboratory Manual, pp 52-55.

Observations and Results: Experiment A: Reigniting a candle wick Observation: The candle reignited when the flame from the match was held close to the smoke trail that was left from the extinguished candle. There was a cracking sound that occurred when the candle was reignited. Results and Explanation: Candle was reignited when the flame touched the smoke trail left from the extinguished candle. When the candle was extinguished, the wax flame turned into a gas state which created a trail of smoke that originated from the previously lit wick. The smoke trail has all of the necessary reactants needed for a combustion reaction. The flame goes through the smoke trail while the wax vapour acts as the fuel to reignite the candle. Experiment B: Water Suck Up Observation: The candle was lit and jar was placed over the lit candle which was sitting in some water. The flame grew slightly larger and soon diminished. After the candle extinguished, the water that the candle and water was submerged in, sucked up into the glass jar. Results and Explanation: The candle extinguished a few seconds after being under the jar and the water sucked up into the jar. The flame uses whatever oxygen is left inside the jar. The jar, which is airtight sealed, which prevents any oxygen from entering which results in the flame extinguishing. The difference in the pressures from outside the jar as well as inside the jar, which will allow the water rise up inside the jar until the pressures equal out to be the same. Experiment C: Extinguishing flame with aluminum foil. Observation: Put the aluminum foil by the wick of the lit candle, after a few minutes the flame from the candle fully extinguishes.

1

Results and Explanation: The aluminum foil prevents the wax down the candle because the heat from the candle bounces off of the aluminum foil. Therefore, if the heat does not melt the wax, and the wax vapor doesn’t travel towards the burning wick allowing it to continue to burn, the candle extinguishes. Experiment D: Candle condensation Observation: When the aluminum foil filled with ice was put by the burning flame, condensation began and water droplets were formed on the outside of the aluminum ice filled sack. Results and Explanation: The main product for the combustion reaction is water. When the ice filled aluminum sack was held over the flame, the water from the combustion reaction appears as little water droplets on the outside surface of the aluminum foil. Experiment E: Extinguishing a candle with Carbon Dioxide Observation: Once the carbon dioxide was poured, the flame of the candle extinguishes after a few seconds. Results and Explanation: When the vinegar and the baking soda mix together, it forms CO2. When the carbon dioxide, which is created from the vinegar and baking soda, it is put over the flame and the oxygen is overtaken. The flame cannot keep burning without oxygen. This is all due to the carbon dioxide being a heavier substance than the oxygen, causing it to extinguish the flame.

Answers to Questions: 1. Why did the candle reignite with a match held away from the wick? The trail of smoke that was created after blowing out the flame had some bits of vaporized wax, which was within the smoke. When the lit match was put close to the trial of smoke from the candle, it attracted towards the wax within the smoke and followed the trail back down to the wick, which reignited the candle.

2. a. Explain how the candle was extinguished with aluminium foil and carbon dioxide. When the aluminum foil was placed between the burning flame and the wax, oxygen was not able to reach the flame to keep burning, which caused it to extinguish. The heat bounced off the aluminum foil which caused it to not burn the wax in order to keep the wick burning. The carbon dioxide that was released when the mixture of vinegar and baking soda reaction, and prevents the oxygen from keeping the flame lit.

2

b. Suggest and explain another method to extinguish a candle not already used in Part A of this experiment. Another method to extinguish a candle that is not already used in Part A of this experiment would be to putting the lit candle in a jar and putting a lid on it completely closing the jar. The oxygen flow will decrease causing the flame to extinguish.

c. Write out the balanced chemical equation for the reaction that produced the carbon dioxide you used to extinguish the flame. Vinegar (Acetic acid) + Baking Soda (Sodium bicarbonate) NaHCO3 (s) + CH3OOH (aq) → NaCH3COO (aq) + CO2 (g) + H2O (l)

3. What does the formation of water on the aluminium ice sack suggest about the chemistry of a burning candle? When the water and the carbon dioxide appear as products of this reaction, it suggests that the candle wax is a hydrocarbon. Therefore when the candles burning, water vapor is formed. The candle flame is hot, while the surface of aluminum foil with ice is cold. When the hot water vapor from the burning flame goes near the cold surface of the foil, liquid droplets form.

4. a. Suggest a reason why the water is sucked up into the glass jar. Once the flame has used up the remaining oxygen in the jar, the pressure inside the glass jar reduces. When this happens, carbon dioxide and water vapor is produced. The water is then sucked into the jar to equalize the pressure with outside the jar.

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? When the combustion happens, more moles of the O2 are consumed than moles of the CO2 produced. Therefore a vacuum is created and water is sucked into the jar to equalize the pressure. The production of CO2 which is a gas, should be considered. The volume change is less than the 20% expected if only considering the O2 consumption. Air is about 20% O2 by volume.

3

5. Explain the difference in the shapes of the two flames (Normal candle and the nearly identical candle in micro gravity flame) shown on page 51 of this manual. The flames on earth are yellow which is due to the carbon particles. The rising hot air is where the tear shape of the flame comes from. Heat from the flame causes expanding of products, and decreases density. The flames at micro gravity are spherical and blue around the wick. For density difference, gravity is needed. Without the flame being able to expand, the spherical shape the flame naturally forms, which prevents oxygen from reaching the wick. The flame will extinguish.

Conclusion: Through examining all of the different ways to alter and manipulate the burning flame of a candle. Many factors may occur and may alter the reaction as well as prevent reaction, like oxygen and air pressure. The inferences include the substances in chemical reactions, fuel from oxygen, the gravity, heat, smoke as well as pressure. Overall the experiment showed different ways a candle can be controlled as well as learning qualitative research laboratory skills during the process.

4...