On Fri, Oct 24, 2014 at 10:57 PM, Jed Rothwell <jedrothw...@gmail.com> wrote:
> H Veeder <hveeder...@gmail.com> wrote: > > >> Ok so you can design a calorimeter to detect this particular endothermic >>> reaction, however, if you don't know a-priori what type of endothermic >>> reaction or what energy source is involved a "standard" calorimeter might >>> fail to detect it. >>> >>> Harry >>> >>> >> Another potential problem is that a calorimeter designed to detect an >> exothermic reaction might prevent an unknown endothermic reaction which is >> a prerequisite for the exothermic reaction. >> > > A calorimeter cannot be designed for exothermic or endothermic reactions. > If it can measure an increase in heat, it can measure a decrease with the > same accuracy and precision. When a reaction produces heat and then stops > producing it, the calorimeter always shows that decline. You always see the > power fluctuating up and down; the calorimeter always measures in both > directions equally well. With an endothermic reaction the decline goes > below the starting point. That's the only difference. The calorimeter does > not care about that. > > If the cell was storing up energy, you would see it for sure. Scott Little > showed a beautiful example of this once. He put a rechargeable battery into > a calorimeter and charged it up. There was a deficit comparing electricity > to the rising temperature. Then he discharged the battery through a > resister in the cell. All the lost energy came back. The balance was close > to zero. > > - Jed > > Was the temperature of the water in the calorimeter rising during charging? Harry
