Question

unit 1 combustion
write 5 things you already know about combustion:
1.
2.
3.
4.
5.
draw the candle before you light it. label all parts.
draw what you see while the candle is burning. give details.
draw the candle after you put it out. give details.
describe what you think is going on during the combustion of the candle. write one paragraph about the changes occurring.

Explanation:

Combustion is a chemical - reaction. It requires fuel, oxygen, and heat (the fire triangle). For the candle - related parts: Before lighting, a candle has a wick and wax. While burning, the wax melts, the wick is alight, and there is a flame with heat and light being produced. After putting it out, there is smoke, and the wax may have cooled and solidified again. During candle combustion, the wax vaporizes and reacts with oxygen in the air to produce carbon dioxide, water vapor, and release energy in the form of heat and light.

1. Combustion is a chemical reaction.
2. It needs fuel, oxygen, and heat.
3. Fire produces heat and light.
4. Combustion can be rapid or slow.
5. Some materials are combustible, others are not.

For the drawing parts:

• Before lighting: Draw a cylindrical piece of wax with a thin wick at the center on top. Label the wax and the wick.
• While burning: Draw a flame above the wick, melted wax around the base of the wick, and possibly some smoke. Label the flame, melted wax, and wick.
• After putting it out: Draw the remaining wax, a slightly charred wick, and some smoke rising. Label the wax, wick, and smoke.

For the paragraph: During the combustion of the candle, the heat from the flame melts the wax near the wick. The liquid wax is drawn up the wick by capillary action. Once at the top, the wax vaporizes. The wax vapor then reacts with oxygen in the air in a combustion reaction. This reaction produces carbon dioxide gas and water vapor, and releases energy in the form of heat and light. As the reaction continues, the wax is gradually consumed, and the candle shortens over time.

Answer:

1. Combustion is a chemical reaction.
2. It needs fuel, oxygen, and heat.
3. Fire produces heat and light.
4. Combustion can be rapid or slow.
5. Some materials are combustible, others are not.

(For drawings, follow the descriptions above)
(Paragraph: During the combustion of the candle, the heat from the flame melts the wax near the wick. The liquid wax is drawn up the wick by capillary action. Once at the top, the wax vaporizes. The wax vapor then reacts with oxygen in the air in a combustion reaction. This reaction produces carbon dioxide gas and water vapor, and releases energy in the form of heat and light. As the reaction continues, the wax is gradually consumed, and the candle shortens over time.)