At 55Cº the wax was visibly melting, especially at the bottom. It went at a steady temperature of about 3-4Cºper minute, it was forming a smooth curve on my graph, and then it rapidly increased by 41Cº in 1 minute.
Soon after, the wax began to solidify. It took 2 minutes to go down to 85Cº. Later on, it went down to 71Cº. After at 56Cº, the stearic acid was visibly solidifying.
At room temperature (24Cº) the particles are close together by a rigid lattice. They only vibrate a little in their fixed positions.
When the particles have gained enough energy from the heat (24-91Cº), they start to vibrate more and they manage to break free from the lattice.
The particles gain then so much energy (91Cº) that they have enough to move around and to escape.
C/W Evaluation 21/05/02
The results of the melting and solidifying curves of stearic acid weren’t the results that I was expecting.
At the beginning when the temperature was 22Cº (room temp) I expected the temperature to increase, but instead, it went down to 21Cº and the next minute it went up again to 23Cº.
After this, the temperature recordings were forming a smooth curve, however, when it was at 60Cºthe temperature rapidly increased by 41Cº in one minute, there wasn’t a smooth curve in my graph. As the temperature was cooling down, there was another odd results, as again, I was expecting the solidifying recordings to form a smooth curve, instead the temperature increased up and then it went down again.
To make this a fair test I could use a draught shield. This could help for some more accurate temperature recordings. The reason that I would use a shield, is to help the heat in, which will help the stearic acid to melt quicker and keep out any cold air from slowing down the melting.
Another thing that could affect the results, is the amount of water there is on the beaker, some of the energy that is released from the heat is absorbed by some of the water particles, this also slows down the progress.
Next time I would use a data logger, the data logger will take more accurate results than me, because it is exact it will take the readings at the exact minute ant the temperatures.
I will also try and use a 2nd clamp stand to hold the thermometer in the centre of the wax, so I wouldn’t have to take out the thermometer every time I need to take a reading, which if I do this it will affect the thermometer reading.
The stearic aid that I used was impure and already used, so next time, I would use pure stearic acid wax to check it does melt at 70Cº. Also repeat the experiment 2-3 times to work out an average of each recording.
