A piece of sodium hydroxide weighing 4.6 g was dropped into 100 ml of distilled water.

A piece of sodium hydroxide weighing 4.6 g was dropped into 100 ml of distilled water. Determine the mass fraction (%) of sodium hydroxide in the resulting solution.

Given: Solution:
V (H2O) = 100 ml 1. Find the mass of the solution, knowing that it is equal to the sum
m (Na) = 4.6 g masses of water and sodium hydroxide, taking into account that
Find: 100 ml of water is 100 g (the density of water is 1 g / ml):
w (NaOH) =? m (solution) = m (NaOH) + m (H2O) = 4.6 + 100 = 104.6 g
2.w (NaOH) = m (NaOH) / m (solution) = 4.6 / 104.6 =
= 0.04 (4%)
Answer: 4%