How To Use Digital Melting Point Apparatus

In this short video, Paul Cook will show you how to use digital melting point apparatus. Using 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:

00:00:10:03 – 00:00:11:13
Hello, I’m Paul Cook

00:00:11:13 – 00:00:17:23
And in this LaBLiFe video we’re going
to look at a melting point apparatus.

00:00:18:05 – 00:00:20:19
We’ve used it recently for an A-level

00:00:21:00 – 00:00:24:00
chemistry required practical

00:00:24:00 – 00:00:27:09
and they’re looking
at the synthesis of aspirin

00:00:28:02 – 00:00:32:18
and we’re going to test the purity
of the substance that they’ve produced

00:00:33:09 – 00:00:36:19
by using this melting point apparatus.

00:00:37:04 – 00:00:43:06
Now, aspirin has a melting point of 135° Celsius.

00:00:45:23 – 00:00:49:20
We need to set our plateau temperature

00:00:50:04 – 00:00:52:24
and what we’ve done is we’ve set it just below

00:00:53:21 – 00:00:56:03
the 135° C.

00:00:56:03 – 00:00:59:03
So what I’m going to do,
I’m going to switch

00:00:59:03 – 00:01:00:17
the unit on

00:01:02:19 – 00:01:04:02
and we’ve got a light

00:01:04:02 – 00:01:08:10
on our viewfinder here
and we can see that we’re starting off

00:01:08:22 – 00:01:11:20
quite low and it’s going to take a little while

00:01:12:22 – 00:01:14:21
for our temperature to rise.

00:01:14:21 – 00:01:18:00
So we’ve got some buttons here.

00:01:18:00 – 00:01:20:13
So we hold down

00:01:23:00 – 00:01:25:21
our plateau temperature

00:01:25:21 – 00:01:28:04
and we increase it

00:01:37:12 – 00:01:39:13
we hold it and we can quickly

00:01:41:06 – 00:01:42:04
go up.

00:01:42:04 – 00:01:47:19
And if we go to 125, we leave ourselves

00:01:49:20 – 00:01:51:15
ten degrees

00:01:51:15 – 00:01:53:21
to our expected melting point.

00:01:55:05 – 00:02:01:02
Now, hopefully our unit will start heating up

00:02:01:05 – 00:02:07:02
quite quickly to our 125° plateau temperature

00:02:30:13 – 00:02:34:13
So in the meantime, while it’s warming up,
I can show you we’ve already

00:02:34:23 – 00:02:39:11
got the unit up on its feet here

00:02:39:12 – 00:02:42:12
so that you can change
the angle of the unit.

00:02:43:24 – 00:02:46:03
And then when we’re going

00:02:46:03 – 00:02:49:05
to use our capillary tube,

00:02:49:20 – 00:02:52:02
we’re going to put them in here,

00:02:53:03 – 00:02:54:11
slide them through.

00:02:54:11 – 00:02:55:09
And if you can see that

00:02:55:09 – 00:02:59:13
there are two slots,
so there are two troughs that you can use

00:03:01:08 – 00:03:04:23
and then we can view them

00:03:05:07 – 00:03:08:16
through this magnified

00:03:09:09 – 00:03:11:14
viewfinder here.

00:03:11:15 – 00:03:14:09
So we’ve got our test sample

00:03:14:09 – 00:03:16:16
that the students have already produced

00:03:16:16 – 00:03:21:09
and here are our capillary tubes.

00:03:34:10 – 00:03:38:03
So I’m going to put my glasses on…

00:03:44:11 – 00:03:49:18
As you can see, it takes a little while
for the unit to heat up.

00:04:02:04 – 00:04:04:10
Okay, so now we’ve reached

00:04:05:04 – 00:04:07:15
our plateau temperature.

00:04:07:15 – 00:04:10:17
All we need to do is

00:04:10:20 – 00:04:14:06
gain our sample

00:04:24:11 – 00:04:28:24
tap off the excess.

00:04:31:04 – 00:04:32:04
Okay,

00:04:33:08 – 00:04:38:02
now I’ve put it into the side in here

00:04:42:10 – 00:04:45:21
I insert it through

00:04:46:12 – 00:04:49:01
I can see the crystals

00:04:52:23 – 00:04:55:10
through the viewfinder at the moment,

00:04:56:01 – 00:04:59:03
so we can see that it’s still a solid.

00:04:59:03 – 00:05:02:23
Now, you can see here
that we’ve got our indicator

00:05:02:24 – 00:05:06:10
to show that we’ve got
our plateau temperature reached.

00:05:06:10 – 00:05:09:17
And what I’m going to do,
I want to press this button to start

00:05:10:17 – 00:05:13:11
temperature ramping so it’s going to go up

00:05:13:23 – 00:05:16:14
in increments of two degrees.

00:05:18:00 – 00:05:20:10
So if I press start now, you can see that

00:05:20:19 – 00:05:23:10
it’s now ramping

00:05:25:21 – 00:05:29:09
and now what you would do is you observe

00:05:30:17 – 00:05:32:24
the capillary tube

00:05:33:09 – 00:05:35:10
for it to show signs

00:05:35:10 – 00:05:38:15
that it’s beginning to melt, sublime.

00:05:38:15 – 00:05:42:15
So you’ll notice that from the outside edges

00:05:44:13 – 00:05:50:23
the substance should begin to liquefy.

00:05:50:23 – 00:05:51:19
So what I’m going to do,

00:05:51:19 – 00:05:55:03
I’m just going to move it now

00:05:55:03 – 00:05:57:07
so that I can

00:05:57:08 – 00:06:02:00
I can observe it

00:06:03:05 – 00:06:05:07
and remember that what we’re looking for

00:06:06:24 – 00:06:12:18
is the temperature of 135 degrees Celsius.

00:06:13:21 – 00:06:18:12
That’s if it’s really pure.

00:06:24:04 – 00:06:27:16
So the temperature is slowly increasing

00:06:32:18 – 00:06:37:06
But we’re now 129 degrees Celsius

00:06:40:13 – 00:06:43:19
130…

00:06:50:00 – 00:06:54:10
So I can still see that it’s a solid.

00:06:57:17 – 00:07:00:09
134…

00:07:24:01 – 00:07:28:20
You can just see that it’s beginning to go.

00:07:37:08 – 00:07:40:18
135, it’s gone.

00:07:42:14 – 00:07:46:05
So you can say that the sample
that the students made

00:07:48:00 – 00:07:50:08
is very, very pure.

00:07:50:08 – 00:07:53:14
And we’ve got an excellent
result from our A-level students.

Enjoyed this blog? Become a LaBLiFer and sign up to our newsletter to get special deals: eepurl.com/h8rb0f