# An excess of copper (II) sulfate solution was added to a solution with a mass fraction of sodium hydroxide of 15%.

An excess of copper (II) sulfate solution was added to a solution with a mass fraction of sodium hydroxide of 15%. This formed a precipitate weighing 24.5 g. Determine the mass of the initial alkali solution. 1) Let’s compose the reaction equation:
2NaOH + CuSO4 = Cu (OH) 2 ↓ + Na2SO4
2) Calculate the amount of the precipitated copper (II) hydroxide:
n (Cu (OH) 2) = m (Cu (OH) 2) / M (Cu (OH) 2) = 24.5 / 98 = 0.25 mol.
3) Determine the amount of the substance, the mass of sodium hydroxide, the mass of the initial solution:
according to the reaction equation
n (NaOH) = 2n (Cu (OH) 2) = 2 ∙ 0.25 = 0.5 mol
m (NaOH) = n (NaOH) ∙ M (NaOH) = 0.5 ∙ 40 = 20 g.
m (solution) = m (NaOH) ∙ 100% / ω (NaOH) = 20 ∙ 100/15 = 133.33 g. Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.