Stearic acid is used for making soap. The
melting and boiling points of stearic acid
are 70°C and 287°C respectively. Sketch a
graph to show the changes in temperature
when molten stearic acid is cooled to room
temperature.
Answers
Explanation:
If by molten, you mean it has completely melted and is at 70 degrees C, then as cools it would stay at 70 degrees until it completely solidified, then it would slowly cool to room temperature, which is about 22-24 degrees C. If it is initially above 70 degrees C, then the temperature would drop until it reaches the melting point, then remain at that temperature until it had turned to a solid. It would then cool as above to room temperature.
The key point when looking at how substances cool (or heat) is that during a phase change the temperature remains constant while the amount of heat energy in the substance either increases or decreases. If the substance is in a single phase - either solid, liquid, or gas - then changes in heat energy result in either increases or decreases in the temperature of the substance.