Available online
Description
The programme utilizes measurements of specific heat at constant pressure to demonstrate path dependent and path independent processes.
The programme utilizes measurements of specific heat at constant pressure to demonstrate path dependent and path independent processes.
| Module code and title: | ST285, "Solids, liquids and gases" |
|---|---|
| Item code: | ST285; 12 |
| First transmission date: | 28-07-1973 |
| Published: | 1973 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:23:18 |
| + Show more... | |
| Producer: | Edward Smith |
| Contributors: | Paul M. Clark; Alan J. Walton |
| Publisher: | BBC Open University |
| Keyword(s): | Continuous flow device; Differential scanning calorimeter; Entropy change; Oscilloscope; Piston cylinder experiment; Specific heat measurement |
| Footage description: | Paul Clark introduces the programme. He looks at examples from the First Law of Thermodynamics to illustrate the difference between path dependent and path independent processes. Clark uses a drawing board to derive the heat capacity at constant pressure and heat capacity at constant volume equations. Alan Walton with apparatus which measures heat capacity. He explains how it works and then points out some disadvantages of this method. Walton next shows a modified apparatus which overcomes some of the errors of the above apparatus. Walton shows another, much more sophisticated apparatus and explains how it works. Walton uses this apparatus to measure heat capacity characteristics of a polyethylene sample. The results are shown on a chart recorder. Walton compares the results with those for a liquid crystal. Paul Clark poses the problem of measuring the heat capacity of a gas with an error of 0.01%? or less. Still shots of apparatus at the National Physical Laboratory capable of taking these measurements. Alan Walton explains how it works. He uses schematic diagrams and photographs of the apparatus as visual aids. Walton uses graphs to show results obtained for isopropyl alcohol with this apparatus. Paul Clark uses an animated graphics board to re-state the original problem: Is heat input path dependent or path independent? He goes on to evaluate this problem using a graphics board as he goes along. Clark uses an analogue computer to evaluate the integrals of the equations. The results are shown on an x, y plotter and oscilloscope and indicate that heat input is path dependent. Clark uses a drawing board and an analogue computer to evaluate the integral (?) and indicates that it is path dependent. |
| Master spool number: | 6HT/70988 |
| Production number: | 00525_1036 |
| Videofinder number: | 689 |
| Available to public: | no |
