What are some assumptions that can be made in a stearic acid experiment. Can someone please respond honestly
Answers
Explanation:
Energy must be supplied to melt a solid; this same energy is released when the liquid re-solidifies.
This presents a good opportunity to demonstrate how to maintain a steady temperature using a Bunsen burner. This can be achieved by sliding the Bunsen burner aside as the boiling becomes too vigorous; slide it back as the water stops boiling. It is not essential that the water bath is boiling. Students could be provided with another thermometer, and asked to maintain a lower temperature, say 80 °C.
A temperature sensor attached to a computer can be used in place of a thermometer. It can plot the temperature change on a graph and show this as it occurs. A slight modification of the experiment can yield an intriguing result: When the test tube is cooling place it in an insulated cup containing a few cm3 of water. Use a second temperature sensor to monitor the temperature of the water. The water temperature should rise as the stearic acid cools and it should continue to rise even as it changes state.
A slight alternative to this experiment is to plot only the cooling curve. Place all the boiling tubes with stearic acid into a large beaker. Place some hot water in the beaker and continue to heat with a Bunsen burner. Remove from the heat when all the stearic acid has melted. Students can place a thermometer into the stearic acid and place the boiling tube into a test tube rack or beaker. They take the temperature every 30 seconds or every minute and plot a graph. Many students will anticipate that the stearic acid will continue to cool to zero – it is useful to discuss why the stearic acid stops cooling when it reaches room temperature.