CHEMISTRY COMMUNITY

The Law of Conservation of Mass makes sense to me, but in lecture the example used was

and he put that it's basically 2 moles of sodium + 2 moles of water = 2 moles of NaOH + 1 mole of hydrogen. Does there not have to be the same number of moles on both sides?

There is the same number of moles of Na, H, and O. This equation does abide by the law of conservation of mass because the mass is equal on both sides.