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Summary Unit 2 A2 Learning aim B: Undertake calorimetry to study cooling curves
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Calibration of thermometersMaking a thermometer for both ungraduated & setting up the beakers with cold water & marking the position
on the thermometer. The method used to calibrate the thermometers using ice water & boiling water as fixed
points was that for the alcohol thermometer which was an ungraduated thermometer. An erasable pen was
used to mark where the fixed points were to see the melting and boiling points, so the lower fixed point was
the measuring of the ice & of the boiling water, but I tried to avoid touching the corners of the beaker to
avoid temperature from the glass impacting the beaker & the water bath temperature was measured too. For
the lower fixed point, the thermometer scale to 0.5 o C to avoid error from the other factors impacting the
temperature. For the graduated thermometer the lower fixed of the ice water was measured and the upper
fixed point of the boiling water. Both of these temperatures were at 0 o C to 100 o C Finally, the digital
thermometer measured the boiling water & cold water at 100.7 o C & 1.4 o C.
Thermometers Lower Fixed Point Upper Fixed Point
Calibrated in
ungraduated 0oC 100o C
thermometer
Calibrated in graduated 0oC 100 o C
thermometer
Calibrated in digital 1.4 o C 100.7 O C
thermometer
The thermometers for calibration of the graduated thermometer how accurate the thermometers were found
to be were pretty accurate considering only measuring the water alone, even though air did hit the blub it did
cause a bit of error, however I made sure to wipe the blub with tissue so that it would give an accurate
temperature inside the water & the ungraduated thermometer was like that too. Moreover, the digital
thermometer had an error probably due to the ice melting away and the room temperature impacting the glass
insulation & the amount of ice put in there and also the size of the volume of the distilled water put in, as it
was roughly put inside, as well as the shape of the ice pieces as it were very small. So, by adding ice
immediately when it was on is on by adding the ice rapidly and pouring the distilled water helped to make
sure that it was cold enough. As well as making sure that the thermometer did not touch the sides of the
beaker, as making sure that when it was clamped not too hard to make sure that the thermometer did not
break. Then once I did that, I needed to make sure that when I took it out the thermometer shouldn’t measure
the air, so when the mercury stopped going down, I immediately noted down what the temperature was then.
I did this accurately due to realising that by holding with my hands, that my hands shaked a lot and my
elbows hurt when I was holding it. So, I suggested to talk an alternative better way to avoid giving myself
too much pressure. I think by doing a trial then the accurate part really did help me to make sure that the
recordings I took were good.
The temperature of the water bath how I worked it out was 50 o C without the scale was because it was in
between 0 to 100 o C & as it was halfway it suggested that it was not either too hot or too cold, so by having
it in between could help to see on the thermometer where it lies, so by knowing the size of the hole, the
length of the tube it has a more of a non-round thermometer body. By having this helped to read the side
which acts like a magnifying glass, which makes the liquid column easier to read. Also, the round
thermometer is still standard and there are a variety of sleeves to put to it which allows it to be used avoiding
the breakage. Due to also I put my finger in the water & tested out what the feeling of the water was, as I
guessed that as I’m in a room temperature I can easily tell what the temperature was, however maybe
because of my body heat that could have impacted too, as when I took out the thermometer from the water
bath, as air straight away hit the bulb it made it more vulnerable for the temperature to go up, so when I saw
that the mercury stopped going up, I instantly with a reusable pen I marked down what the temperature was.
Moreover, I think that also due to the other classes using the thermometer that could have impacted too on it,
so the pressure exerted on the thermometer bulb can affect the readings & so will have an impact on the
accuracy. I realised that when I immerged into too deep the temperature was going up, but when I did it
above just a bit, I think that the air made the mercury go down. Thermometers are designed to measure not
, when it is fully immersed into the liquid. The thermometer can help to monitor the endothermic/exothermic
reactions
In the experiment you needed to put solid wax in a boiling tube I used the wax as much as it covered the
thermometer blub which was around 4-5cm, this is so that the thermometer will not touch the sides of the
boiling tube and cause temperature difference, even though I can manage the measure the boiling tube and
subtract how much was measured to avoid uncertainty. Then by heating the boiling tube I used clamps,
clamp stands, & bosses to hold the boiling tube so that there isn’t error whilst I was holding it & also so that
I didn’t put pressure on myself, finally that even if I touched the paraffin wax it wouldn’t harm me, due to it
being wax only when solidified, however it would harm me if I touched the wax when it was liquidised.
Removing the boiling tube with the liquid from the hot water. So, by having the boiling tube supported by
the clamps to have placed it in accurately in the wax, so that only the wax was measured and not the air. The
boiling tube would not need insulating, as the goal of the experiment to figure out the liquid state and the
solid state. The thermometer how it is supported is by the bosses & the clamp & attaching to hold the
thermometer, & the time intervals I decided to measure at is every 1 minute due to the liquid solidifying fast
& once I stopped it at 48 o C.
Results for cooling of stearic acid (first experiment))
Time (mins) Temperature ( degrees
o
C)
1 68
2 64
3 60
4 57
5 56
6 55
7 55
8 55
9 55
10 54
11 54
12 54
13 54
14 54
15 53
16 53
17 53
18 53
19 52
20 52
21 51
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