How the mass changes during of a candle illustrate your observation with the help of activity.
Answers
Answer:
Explanation:
Objectives:
1. Carefully observe and describe the characteristics of a candle flame.
2. Determine what is necessary for a candle to burn.
3. Determine the products of the combustion of a candle.
Materials: (pair of students)
Large wax candles 2
Matches 1 book
Shallow plastic or metal 1
10 ml of phenol red solution 25 ml
250 ml beaker 1
250 ml Erlenmeyer flasks 1
Rubber stopper to fit the flask 1
Wire gauze square 1
Tongs 1
Safety:
Keep all flammable materials away from matches and burning candles.
Wear safety goggles.
Procedure:
1. Light a candle and let 3-4 drops of wax fall in to the center of the pan. Press the candle into the melted wax and hold it upright until the wax solidifies
2. Light the candle. Carefully observe the flame. List at least 8 observations of the flame. Look at the colors and the shape of the flame. Where does the burning take place? What is burning?
observations
1
2
3
4
5
6
7
8
3. When a chemical change takes place, a different substance is formed. When a physical change takes place, the substance changes shape or phase, but the substance remains the same. Classify each of the following as a chemical (C) or physical (P) change.
a. _____ wax melting
b. _____wick burning and turning in to soot
c. _____wax burning and forming carbon dioxide
d. _____breaking a glass
e. _____baking cookies
f. _____digesting food
4. Light a second candle and hold the flame 2-4 cm from the flame of the first candle. Gently blow out the first candle flame and then move the other flame in to the smoke from the first flame. Do you have to touch the wick in order to get the candle to relight? Write your observations below. What does this tell you about the part of the candle that is burning?
Observations
5. Relight the standing candle and blow out the second candle. Using a tongs, hold the wire gauze over the flame, perpendicular to the flame. Slowly lower the gauze on to the flame. Do not touch the wax. If the flame appears to go out, quickly move the wire gauze to the side. Record your observations. What do you thick is happening? What does this say about the part of the candle that is burning?
Observations
6. Place approximately 150 ml of ice water in a 250 ml beaker. Dry the outside of the beaker. Hold the beaker about 4-5 cm above the flame. Look for the formation of a new compound on the bottom of the beaker. Note: you may see the formation of black soot on the bottom of the beaker. That is not the compound that we are looking for. If you see soot, you are probably holding the candle too close to the flame. Record your observations. What do you think the compound is? Where do you think that the compound came from?
Observations
7. Pour water in to the pan that the candle is in to a depth of 1cm. Quickly lower the mouth of the Erlenmeyer flask over the candle so that the mouth of the candle is below the surface of the water. Hold the flask in place for approximately one minute. After 1-2 minutes, lift the flask out of water and quickly place the rubber stopper in the mouth of the flask. Record your observations below.
Observations
8. Add 10 ml of phenol red solution to the flask. Stopper the flask and swirl the solution for about 1 minute. Record your observations below. What does this tell you about the gas that was formed?
Observations