when can you assume molality and molarity are equal?
 If we assume that the density of the solution is almost equal to that of pure water (1 kg/L), then we find that 1 L of solution will weigh 1 kg. If 1 kg of solution contains 0.0001 M of sucrose , then it is 0.0001 m in sucrose, so the molarity and molality are almost the same. 