Lab+5+Thermal+Combustion

Vaporization Temperatures: -alcohol 79oC -candle wax 896-1130oC -paper 450oC

The cool air around the candle is forced towards the flame as it heats up. As it heats up, it keeps the outside of the candle cool, but the inside of the candle melts from the heat of the flame
 * Questions**
 * Why do candles form a cup?**

The ignited wick melts the wax within the cup
 * What is melting the wax inside the cup?**

When the candle burns, the wick draws up liquid gas in the flame where it is then vaporized
 * What happens to the wick as the candle burns?**

The bottom part of the wick were the blue shaded flame is
 * Where is the hottest part of the flame?**

Yellow part where it is almost white
 * What color is the flame where it gets the most oxygen?**

Lower part of flame which is hollow
 * Where is the coolest part of the flame?**

Hollow shell around flame
 * What is the yellow part of the flame?**

Emitting light due to the fact of being heated
 * What does incandescent mean?**

2 ways of doing it. One, takes place of oxygen that fire needs to burn. Two, it turns to steam that cools the fire so it can no longer burn
 * Questions Continued....**
 * How does water put out fires?**

Releases CO2 which displaces oxygen that is essential for a fire to burn
 * How does CO2 extinguishers put out fires?**

Want to put out the fire at direct source
 * Why are people instructed to aim extinguishers at the base of the fire?**

Because there is an instantanious addition of oxygen to the fire
 * Given what you know about oxygen and combustion, why do you think opening a door in a burning building causes an explosion of the fire outwards (also known as a back draft)?**

Flour explodes because it is a starch, and chemical make up of flour allows it to burn
 * There are two rooms, one filled with particles of dirt suspended in the air, the other has particles of flour suspended in the air. A match is lit and the room filled with suspended flour particles explodes, but the room with dirt doesn't. Why not?**

In order for flour to burn, it must be spread out so it can gain oxygen
 * Why doesn't a pound of flour sitting on the ground burn when a match is tossed onto it, but a room of suspended flour particles explodes?**

Alcohol must be heated so it can get enough energy to reach desired burning stage or else won't have enough energy to gain heat to burn
 * Why does the alcohol for flambee deserts need to be heated or the alcohol won't burn?**


 * Materials**
 * organic tea candle**
 * matches**
 * thermocouple**
 * beakers**
 * tin foil**
 * ice**


 * A. Re-igniting a Candle**

1. Light a candle and let it burn for about one minute. 2. Have a lighted match or lighter ready. 3. Carefully blow out the candle. 4. Watch the smoke trail coming up from the extinguished candle and quickly place your lighted match into that smoke stream. 5. The candle should re-ignite.


 * Describe what happened in scientific terms using what you have learned about the burning of candles and combustion**

When candle is extinguished, oxygen that wasn't promptly burned rises from wick. When relit match is put into unburned oxygen, that oxygen is relit. Combustion travels down oxygen stream to relit wick.
 * B. Candle Condensation**

1. Place a small amount of crushed ice on a spoon or small square of aluminum foil. 2. Pull together the corners to form a sack filled with ice. 3. Hold this sack about 20 cm over a burning candle. Any lower and all you may see is soot form. 4. Water droplets should form on the outside of the aluminum sack or spoon.


 * Describe what happened in scientific terms using what you have learned about the burning of candles and combustion**

Water formed on outside of tinfoil due to condensation. Gas released from burning candle touched cold foil which formed water.

1. Put a metal spoon or a small square of aluminum foil in the freezer and follow directions 'Certain products...' at the website you were reading.
 * C. Incomplete combustion**

**Describe what happened in scientific terms using what you have learned about the burning of candles and combustion.**  ﻿ Caused by condensation around spoon. Burned hydrogen and oxygen from the cane hit the cold spoon to form water. Effect doesn't last due to continuation of spoon be heated. **﻿**      **D. Extinguishing a Candle with Carbon Dioxide**  1. In a glass or large beaker put 1/2 teaspoon of dry baking soda in the beaker towards the edge. 2. Place a lit candle in the beaker (there are tongs). 3. Using a pipette, dribble a little vinegar onto the dry baking soda. 4. The baking soda will foam. Be careful not to tip the wet vinegar/baking soda mixture into the candle. 6. The candle should extinguish.

Describe what happened in scientific terms using what you have learned about the burning of candles and combustion

<span style="display: block; font-family: Arial,Helvetica;">**﻿** <span style="display: block; font-family: Arial,Helvetica;">**﻿** <span style="display: block; font-family: Arial,Helvetica;">**﻿** <span style="display: block; font-family: Arial,Helvetica;"><span style="display: block; font-family: Arial,Helvetica;"> CO2 from mixture of vinegar and baking soda was more present than oxygen in the beaker. This displaces oxygen that fire needed. <span style="display: block; font-family: Arial,Helvetica;"> <span style="display: block; font-family: Arial,Helvetica;"> <span style="display: block; font-family: Arial,Helvetica;"> <span style="display: block; font-family: Arial,Helvetica;"> <span style="display: block; font-family: Arial,Helvetica;"> <span style="display: block; font-family: Arial,Helvetica;"> <span style="display: block; font-family: Arial,Helvetica;">**E. Oxygen** <span style="display: block; font-family: Arial,Helvetica;"> <span style="font-family: Arial,Helvetica;"> 1. Place a candle in a bowl. (there are also tin plates) 2. Light the candle. 3. Place an empty jar or glass over the candle. 4. The candle should extinguish. <span style="font-family: Arial,Helvetica;"> Candle burned up all available oxygen that was trapped between the two beakers, and had no more oxygen required for it to burn. <span style="display: block; font-family: Arial,Helvetica;"><span style="font-family: Arial,Helvetica;"> <span style="display: block; font-family: Arial,Helvetica;"><span style="font-family: Arial,Helvetica;">  <span style="display: block; font-family: Arial,Helvetica;"><span style="font-family: Arial,Helvetica;">  <span style="display: block; font-family: Arial,Helvetica;"><span style="font-family: Arial,Helvetica;">  <span style="display: block; font-family: Arial,Helvetica;"><span style="font-family: Arial,Helvetica;">  <span style="display: block; font-family: Arial,Helvetica;"><span style="font-family: Arial,Helvetica;">**F. Gases** 1. Pour water into the bowl so that it is partially filled. (there are also tin plates) 2. Place a lit candle in the bowl. 3. Place an empty jar or glass over the candle so that the edge is under the water line (a tall narrow glass works best!) Be sure to WAIT after the candle goes out. That is when something happens.
 * <span style="font-family: Arial,Helvetica;">Describe what happened in scientific terms using what you have learned about the burning of candles and combustion. **

<span style="font-family: Arial,Helvetica;"> Candle burned all available oxygen and created a vacuum like aparatus that caused the water to flow under the candle and made it float.
 * <span style="font-family: Arial,Helvetica;">Describe what happened in scientific terms using what you have learned about the states of matter in lecture. Why does what you observed with the water happen? You may need to do a search. **