Calorimeter Experiment

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En provenance du cours de University of Manchester

Introduction to Physical Chemistry

251 notes

University of Manchester

Introduction to Physical Chemistry

251 notes

Chemical reactions underpin the production of pretty much everything in our modern world. But, what is the driving force behind reactions? Why do some reactions occur over geological time scales whilst others are so fast that we need femtosecond-pulsed lasers to study them? Ultimately, what is going on at the atomic level? Discover the answers to such fundamental questions and more on this course in introductory physical chemistry. The course covers the key concepts of three of the principal topics in first-year undergraduate physical chemistry: thermodynamics, kinetics and quantum mechanics. These three topics cover whether or not reactions occur, how fast they go and what is actually going on at the sub-atomic scale.

À partir de la leçon

Virtual Lab 1: Thermodynamics

This lab allows you to further explore thermodynamics.

Introduction to Experiment5:00

Calorimeter Experiment28:03

Rencontrer les enseignants

Patrick J O'Malley, D.Sc
Reader
Chemistry
Michael W. Anderson, FRSC
Professor of Materials Chemistry
School of Chemistry
Jonathan Agger, MRSC
Lecturer and Deputy Director of Outreach
Chemistry

[BLANK_AUDIO].

Okay, welcome back.

So here's the experimental setup once again,

so you can familiarize yourself with it.

The calorimeter is a vacuum-sealed joule flask with a rubber lid and

electronic steering mechanism, which you can

see turning and a highly accurate thermometer.

[BLANK_AUDIO].

So, for the calibration reaction, accurately weigh

out 11.30 grams of powdered sodium nitrate.

[NOISE]

[BLANK_AUDIO].

Transfer the powder to a 100 milliliter volumetric flask by

rinsing it from the weighing boat with a wash bottle.

[BLANK_AUDIO].

Now add distilled water to just short of the mark.

[BLANK_AUDIO].

Make the solution accurately up to the mark adding distilled water via dropping

pipe until the base of the meniscus is perfectly aligned with the mark.

[BLANK_AUDIO].

Stopper the volumetric flask and then

mix the contents thoroughly by repeated inversions.

[BLANK_AUDIO].

Next, transfer 600 milliliters of distilled water to the calorimeter.

[SOUND] And then add approximately five grams of sulfuric acid.

[BLANK_AUDIO].

Next, place the lid on the calorimeter, being careful not to

damage the thermometer and make sure the lid is tightly fitted.

[BLANK_AUDIO].

Then attach the stirrer cable and tighten with an allen key.

[BLANK_AUDIO].

Switch on the stirrer, and I'll add 10 minutes for the sulphuric acid

to dissolve completely and for an

equilibrium rate of temperature to be established.

We're going to jump 10 minutes ahead in time, so you don't need to wait.

[BLANK_AUDIO].

The initial temperature of the reactor at time zero is 19.18 degrees centigrade.

You should have this written down.

We start the chronometer.

And you now need to take temperature readings at one minute intervals

for five minutes in order to define the slope of the pre-reaction period.

I will rejoin you again shortly before five minutes have elapsed.

[BLANK_AUDIO].

On five minutes, we put ten mils of the sodium nitrate

solution into the calorimeter through the glass tube in the lid.

The temperature will rise rapidly.

[BLANK_AUDIO].

By six minutes, the reaction should be complete.

Now, continue taking readings of one minute from six minutes

to 10 minutes to establish the slope of the post-reaction period.

I will rejoin you after 10 minutes has elapsed.

[BLANK_AUDIO].

[SOUND] Okay.

You should now have your 10 readings.

All that remains to be done now is to empty,

clean, and dry the calorimeter, ready for the next run.

[BLANK_AUDIO].

So, for the decomposition of hydrogen peroxide, weigh

out roughly six grams of manganese dioxide catalyst.

[BLANK_AUDIO].

Place this to one side.

[BLANK_AUDIO].

Now transfer 600 milliliters of distilled water to the calorimeter.

[BLANK_AUDIO].

Once again, place the lid on the calorimeter, being careful not to

damage the thermometer, making sure the lid is tightly fitting.

Then attach the stirrer cable and tighten once again with an allen key.

[BLANK_AUDIO].

Switch on the stirrer, then pipette 10 milliliters

of the hydrogen peroxide solution into the calorimeter.

Again, allow 10 minutes for thermal equilibration.

We are going to skip this part.

[SOUND]

[BLANK_AUDIO].

The initial temperature of the calorimeter times zero is 19.43 degrees centigrade.

You should have this written down.

We start the chronometer and take temperature readings again at one minute

intervals for five minutes to define the slope with the pre-reaction period.

So I'm going to leave you now to get

on with that, and I'll be back in five minutes.

[BLANK_AUDIO].

On five minutes, we have the manganese dioxide through the

open glass tube in the lid to catalyze the decomposition.

The temperature rises rapidly once again.

By six minutes, the reaction should be complete.

Now continue taking readings at one minute intervals from six minutes

to 10 minutes to establish the slope of the post-reaction period.

I'll see you again after 10 minutes have elapsed.

[BLANK_AUDIO].

Okay.

You should now have taken your tenth and final reading.

Now we empty, clean, and dry the

calorimeter once again, and the experiment is finished.

Now consult the experimental sheet, which should guide you step-by-step

through the calculations you need to perform to calculate values for

the enthalpy of decomposition of liquid hydrogen peroxide, and the

D, H, O, O, H, bonded association of energy hydrogen peroxide.

You'll be assessed on the two values calculated.

Good luck.

[BLANK_AUDIO]

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