To the zinc chloride solution was added a potassium hydroxide solution weighing 28 g and a mass fraction

To the zinc chloride solution was added a potassium hydroxide solution weighing 28 g and a mass fraction of potassium hydroxide 20%. Determine the mass of the sediment. What mass of potassium tetrahydroxozincate can be obtained by adding an excess of potassium hydroxide.

Decision:
ZnCl2 + 2KOH = Zn (OH) 2 + 2KCl
n (KOH) = m (p-pKOH) * w (KOH) / M (KOH) = 28 * 0.2 / 56 = 0.1 mol
n (Zn (OH) 2) = 0.5 * n (KOH) = 0.05 mol
Zn (OH) 2: m (Zn (OH) 2) = n (Zn (OH) 2) * M (Zn (OH) 2) = 0.05 * 99 = 4.95 g
2KOH + Zn (OH) 2 = K2Zn (OH) 4
n (K2Zn (OH) 4) = n (Zn (OH) 2 = 0.05 mol
m (K2Zn (OH) 4) = n (K2Zn (OH) 4) * M (K2Z (OH) 4) = 0.05 * 211 = 10.55 g
Answer: 10.55g