Experimenting with alcohol
After Geoff's comment on my last blog post I thought I'd try to experiment with alcohol. That doesn't sound so good. What I mean is that I'd try heating alcohol with my hand to see if the difference in specific heat capacity has any affect. I used some hand cleaning fluid which as it is the strongest alcohol we have in the house (85% it says on the bottle). I first tried with a digital thermometer and got fairly consistent results from five runs heating water from about 16.5 to 21 °C in 60s. (The average rise was 5.6 ± 0.4 °C). With the alcohoI was expecting a larger rise but only managed from 20 to 24.5°C. To investigate further I decided to use the vernier probe resulting in the curves shown. The blue curve is water and the others alcohol (I think they are orange red and green but I could be wrong). From these curves it can be seen how dependent the rate of temp change is on the temperature of the fluid. For the orange run I cooled the alcohol down in the fridge. This makes a big difference, the rate of temp. rise at the start is now about twice as big as the water. At higher temps the difference in gradient isn't so big, maybe the alcohol is evaporating?