NaOH + H20 produces ??? Need balanced equation. And why is heat released (exothermic)?

Question

can it melt roots in a sewer line? (clean out provides the venting outside).

Answer 1

Adding solid NaOH to water produces a lot of heat, i.e. high heat of solution. A strong solution of NaOH will react with grease, oil and many other things to clean out a blocked drain pipe. It will not "melt" roots but will react with a lot of the stuff that has attached itself, and hence clean out the drain line.

Answer 2

When you dissolve NaOH in water, it isn't reacting, it just dissolves; it just happens that some substances give off heat when they dissolve (CaCl2 also gives off heat when dissolving). Some substances, such as ammonium nitrate, absorb heat when dissolving, and cause the solution to get cold.

The reason for NaOH being used to clean out plugged drains is not so much the heat of solution (although it helps) but that is a strong caustic and breaks down grease, hair, etc which are the cause of most clogs. If you have got tree roots in the drain line I think it would take a LOT of NaOH, as you would need to keep the whole line filled with the solution for some time to kill the roots. Even if it kills the roots, it might not dissolve them, so it might not work, because dead roots clog the pipe just as good as living roots. You might be better off hiring someone to clean out the line with one of the special machines that are made for this purpose. (You might be able to rent one of the machines if you want to do it yourself).