Question

Some salts work better than salt to melt ice on driveways and roads, not only because they depress the freezing point, but because they have a negative enthalpy of solution (delta H_soln). Do some research and propose a salt that might work in this manner.

Answer 1

Most of the salts shows depression in freezing point in water when dissolved in water.

But some salts are much better than other because the enthalpy of solution ( $\Delta$ H_soltn.) of those salt is negative. So when these salts are dissolved in water they produces energy which used to melt the ice.

So, see the experiments of your last semester and find those salts which have negative enthalpy of solution ( $\Delta$ H_soltn.).