Thursday, 23 May 2013

Sweat content and cooling

This is an experiment to investigate how the electrolytes that make up part of sweat affect the cooling rate due to evaporation.

Equipment

Thermometer
Cotton wool
Elastic band
Clamp and stand
Stopclock
Salt solutions of five differing concentrations (10g/litre - 50g/litre in 10g/litre steps)

Method

Wrap a wad of cotton wool around the thermometer and secure in place with an elastic band.
Dip the wool in the lowest concentration salt solution, stir to it is thoroughly soaked.
Gently shake off any excess, clamp in place, note the initial temperature and start the stopclock.
After 10 minutes note the final temperature.
Repeat using fresh cotton wool for each of the other salt solutions.

Care should be taken to try and ensure the same amount of cotton wool is used each time.
If you have access to 5 thermometers all experiments can be run at the same time.
A digital temperature probe and datalogger will allow you to capture the cooling curve for each experiment if you are able to use one.