Investigating Changes in Temperature During Heating of Solids
Lauric acid is a solid that is found in coconuts and processed foods that are made with coconut oil. Lauric acid is also used to make some soaps and cosmetics. In this lab, you will measure the temperature of ice and of lauric acid as these solids are heated and melt. You will graph the data you collect and compare the heating curves for ice and lauric acid.
Problem What happens to the temperature of a substance during a phase change?
Materials
500-mL beaker
crushed ice
thermometer
hot plate
clock with second hand
test tube of lauric acid with thermometer
glass stirring rod
graph paper
For the probeware version of this lab, see the Probeware Lab Manual, Lab 1.
Skills Measuring, Using Graphs
Procedure
Part A: Heating Ice
On a sheet of paper, make a copy of the data table shown. Start with 11 blank rows, but leave space below your data table to add more rows, if necessary.
Fill a 500-mL beaker halfway with crushed ice. CAUTION Use care when handling glassware to avoid breakage. Wipe up any spilled ice right away to avoid slips and falls.
Place the beaker on a hot plate. Don't turn the hot plate on yet. Insert a thermometer into the ice. Because it takes several seconds for the thermometer to adjust to the temperature of its surroundings, wait 20 seconds and then measure the temperature of the ice. Record this temperature next to the 0 minutes entry in your data table.
Turn the hot plate to a low setting. CAUTION Be careful not to touch the hot plate because contact with the hot plate could cause a burn.
Observe and record the temperature at oneminute intervals until all the ice has changed to liquid water. Circle the temperature at which you first observe liquid water and the temperature at which all the ice has changed to liquid water.