Name________________________________ Block__________ Date___________________
1.7: Making a Cooling Curve and a Heating Curve for Candle Wax (Guided Inquiry)
Your task is to design an experiment to determine the cooling curve of candle wax. In other words, you
will need to construct a graph showing the change in Temperature vs. Time for the substance. The
requirements are as follows:
Cooling Curve
o You may use any of the materials provided to you.
o Your measurements should begin while the wax is in the liquid phase and continue until the wax
solidifies into a solid.
o Before you begin your experiment, you need to write a step-by-step procedure and construct a
data table in which you will record your collected data.
o Mr. Baker needs to “ok” your procedure and data table before you begin.
o You must record data (take temperature measurements) for 30 minutes.
Heating Curve
o You may use any of the materials provided to you.
o You will begin while the wax is in the solid phase and continue until the wax liquefies into a
liquid.
o Before you begin your experiment, you need to write a step-by-step procedure and construct a
data table in which you will record your collected data.
o Mr. Baker needs to “ok” your procedure and data table before you begin.
o You must record data (take temperature measurements) for 30 minutes.
********BE CAREFUL TO KEEP THE PROBE CORD CLEAR OF THE HOT PLATE!*******
I.
Procedure (write neatly)
Write a step-by-step procedure for determining the cooling curve of candle wax.
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Available Materials: 600mL beaker Test tube with candle wax *LabQuest and Temperature Probe Hot plate Water Ice Bath Test tube clamps Graph paper Signature ________
II. Data Table:
Construct a data table that you can use to record the data you collect in your experiment. Remember,
you need to collect data for 30 minutes. Be neat, label correctly, and don’t forget units!
III. Predict what the cooling curve (graph of temperature vs time) will look like for candle wax as it
cools from a hot liquid to a cool solid (use blue to indicate the cooling curve). Collect the data from a
group that was collecting data for candle wax as the solid is heated to a hot liquid and predict what the
heating curve will look like (use red to indicate the heating curve). Don’t forget to provide a title, label
axes, and include units!
Name________________________________ Block__________ Date___________________
1.9: Making a Cooling Curve for Candle Wax
Purpose Determine the melting/ freezing point of candle wax by collecting temperature data, making a graph and then analyzing the graph. Materials Needed ❒
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600mL beaker Test tube with candle wax & thermometer Hot plate Ring stand with 2 clamps Water (from sink) Procedure 1. Fill the beaker with 400 ml of water. 2. Place this beaker on the hot plate and heat. 3. Place the test tube containing candle wax & thermometer in the water. Make sure that the test tube is NOT resting on the bottom of the beaker. Use the clamp to prop it up. 4. As the substance is melting, make sure the thermometer does not fall and hit the bottom of the test tube. 5. Once the substance in the test tube has completely become a liquid, remove the test tube from the hot water by carefully raising the clamps on the ring stand. Make sure that the bulb of the thermometer DOES NOT touch the side or bottom of the test tube. 6. Turn off the hot plate and leave the beaker of water to cool. 7. Record the temperature (this is time 0). Also, note the state of matter (L=liquid; S=solid; S/L=solid AND liquid) 8. Continue to take the temperature and the state every minute for the next 30 minutes. Clean-­‐up 1.
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When you are done, leave the beaker and hotplate on the lab bench. Leave the test tube containing wax and the thermometer clamped to the ringstand. Wipe down your lab bench. Wash your hands. Data, Analysis, Conclusion Separate sheet. Time (min) Temp (° C) 0 1 2 3 4 5 6 7 8 9 10 Data for the Cooling Curve of Candle Wax Phase Time Temp (° C) Phase Time (min) (min) 11 21 12 22 13 23 14 24 15 25 16 26 17 27 18 28 19 29 20 30 Temp (° C) Phase Data Analysis Construct a graph to show how temperature depends on time. Make sure to follow the guidelines & include the following items: ❒
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Put the independent variable on the x-­‐axis and the dependent variable on the y-­‐axis Use the bulk of the graphing area Include a title Label axes with label & unit Plot the points Sketch a smooth curve that represents the trend of the data. Conclusion Questions: Remember: temperature is a measure of the average kinetic energy of the particles in a sample of matter. 1. Using your graph, what is the freezing point of candle wax? ° C K ° F 2. Describe the shape of your graph during the actual changes of state (while the substance is actually solidifying). 3. Consider the diagonal region of the cooling curve. What is happening to the kinetic energy of the particles as the temperature is decreasing? 4. During the cooling process, heat is continually being removed from the sample, yet the temperature remains constant during the actual freezing process. If the constant temperature indicates no change in kinetic energy, then what form of energy is changing? 5. During the freezing, what is happening to the candle wax particles? Heating/Cooling Curve • When temperature changes, there is a change in • When phase changes, there is a change in energy. energy.