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Temperature change in solution relative to concentration
The aim of this experiment is to find out how the amount of salt in a fixed amount of water relates to the temperature change during dissolving of the salt. To find out - is the temperature change directly proportional to the amount of salt? If so, is there a constant of proportionality with which one can make an accurate equation? This equation could be used to work out how much the temperature of the water would lower by knowing just the amount of salt and water mixed, if the outside temperature is fixed.
When salt is dissolving there is an endothermic reaction and so the waters temperature lowers. Salts are ionic compounds. To dissolve the salt, bonds between the ions need to be broken. This takes energy and so heat energy is taken in, making the reaction endothermic.
More salt means there are more bonds to break and more heat energy is taken in, lowering the temperature further. Water molecules are held together by hydrogen bonds. To allow dissolving, these hydrogen bonds need breaking and so take heat energy to do it, making this endothermic too. The ions and water are attracted to each other. Solute-solvent bonds are formed, making the solution. The solution is more stable so it gives out energy, making this part exothermic. If more heat energy is taken in to break apart the ionic bonds than heat energy released when the solute bonds are made, the overall reaction is endothermic. If less heat energy is taken in to break apart the ionic bonds than heat energy released when the solute bonds are made, the overall reaction is exothermic. The two can also be balanced meaning little or no change...