First, they may want you to say that NaCl is bound in a crystal with the Na+’s attracting all the cl-s. Then water comes along and hydrates the ions enabling them to leave one another and enter the solution.
Second, you may be talking about a so called born haver diagram which considers melting and boiling NaCl so that you have a gas of Na+’s and Cl-‘s then you calculate the amount of energy you get when putting the gas ions in water.
