How To Use Analogue Melting Point Apparatus

In this short video, Paul Cook will show you how to use analogue melting point apparatus. Like the digital version, Paul uses the required A-level Chemistry practical example where the students look at the synthesis of aspirin, Paul will demonstrate how to test the purity of the substance they’ve produced. Make sure to watch until the end for extra tips!

Video transcript below:

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Hello, I’m Paul Cook

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and in this LaBLiFe
video, we’re going to look

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at an analogue melting point apparatus.

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Before in a previous video,
we looked at a digital version,

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but you can see already
that there’s quite a bit of difference.

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So we’re going to be using a thermometer
here.

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So we’re going to have to read

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the temperature
that our substance melts at

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we’ve also got here,

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a variable temperature dial.

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And you can see here
that we’ve got three different ranges.

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We’ve got a low,
a medium and a high range.

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So the low range has a maximum temperature

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of around 60 degrees Celsius

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and medium range has a maximum temperature

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of 160 degrees Celsius to 180 degrees Celsius.

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Now, we’re measuring a substance

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that our A-level students have produced
from their required practical.

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They have produced a sample of aspirin.

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and we know that aspirin has a melting

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point of 135 degrees Celsius.

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So we need to use the medium range

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on the dial here.

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So what I’m going to do,

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I’m going to turn the unit on.

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You’ve noticed that you can also use

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(we turn the dial here)
and we can use this rapid heat.

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Just put it just within the medium range

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and I’m going to switch the rapid heat on.

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We just need to carefully
watch the temperature on our thermometer.

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Now, I’ve got a sample here

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in a capillary tube
that I’ve already prepared.

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And you can see here, if we look

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that the unit has three sample slots

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so we can put three different samples in.

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So we just put our capillary tube in

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like this, and then hopefully you can see it

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in our magnified viewfinder here.

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So our unit is heating up

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and I can already see

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the thermometer rising.

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Now what we do, we know that our expected

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melting point is around 135 degrees.

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And we need to keep a close eye on this

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so we can view

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our sample and I can see it

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quite clearly,
and I can see that it’s clearly solid.

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We also need to keep an eye on
our thermometer that it’s rapidly rising

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now using this rapid heat function.
Once it gets to around

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100 degrees, maybe 110,

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120, switch this off

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and rely on the
normal temperature heat on the dial.

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You must keep a constant view

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on your sample and try and keep

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a look on the thermometer to make sure
that you get an accurate reading.

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And so hopefully the sample that we’ve got

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is pure enough
that it should go and begin to melt

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between 134 and 135 degrees C.

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