Hiking, fishing, small repairs of the car on the way to nasty cold weather, when no longer listen to the frozen fingers of the hand, there appears a need in an ordinary heating pad. Naturally, a great warm up by the campfire, but not always it can be diluted, so it will demand time and daze. And if you make a little chem pad? It does not take much space and will always be at hand.
For such heating pad will come in handy the most common reagents. Conduct easy experience. Take of salt, two teaspoons of salt (20 g), then slightly copper sulphate three teaspoons (40 grams). Will resotre them separately in a mortar so that the size of the crystals (in the pelvis) were less than 1 mm Laborious mix, add 5 tablespoons (30 g) small dry sawdust. In a jar of mayonnaise put a piece of aluminum wire, bent spiral or snake, and heap up the cooked mixture to a level at 1-1,5 cm below the bottle opening.
Warmer in your hands. To put it in action, rather pour into the jar a quarter Cup of water (50 ml). After 3-4 min the temperature of the heater rises to 50-60°C.
Where does the heat and the role of any of the components of the texture? Refer to equation occurring in the Bank chemical reactions:
CuS04 + 2NaCl = Na2S04 + in cuci2
In the result of the interaction of copper sulphate with sodium chloride appears sodium sulfate v chlorine copper. If we calculate the thermal balance of the reaction, it appears that during the formation of one gram-molecule of chlorine copper is allocated 4700 calories. This heat will increase 24999 calories allocated when dissolved in water initial and resulting from the reaction products. Adding them, we get about 29600 calories.
But that’s not all, chloride copper immediately reacts with aluminum wire:
2Al + 3CuCl2 = 2AlCl3 + ATP
With all this vydelyaetsa (again in terms of one gram-molecule of chlorine copper) of about 84,000 calories.
As litsezreem, E. the end of the process in mayonnaise Bank any gram-molecule chemical substances will emit more than 100,000 calories of heat. So warmer is the most real, without cheating.
Sawdust does not take any role in chemical processes, but abundantly absorbing E. water, slow the course of the reaction. In addition, wood has low thermal conductivity and the like accumulates heat is evenly giving it out. Tightly closed heat is retained very little for two hours.
Packaging under a warmer suit any materials that can withstand temperatures above 80°.
The pad is made of glass — not a very comfortable and functional, so it is better to take some or the other — not fragile vessel.