Question

1. смешали 160 г 20% раствора и 40 г 50% гидроксида калия массовая доля щелочи в полученном растворе равна 2. из предложенного перечня типов реакция выберите два типа реакции к которым можно отнести реакция между растворами фосфата натрия и нитрата кальция а) обратимая б) обмена в) замещения г) необратимая д) окислительно-восстановаительная

Answer 1

1) 10% 200г
2)обмена и необратимая

Answer 2

I will answer in detail.

1. To find the mass fraction of alkali in the resulting solution, we need to calculate the mass of alkali and the mass of the solution. The mass of alkali in the 20% solution is 0.2 * 160 = 32 g. The mass of alkali in the 50% solution is 0.5 * 40 = 20 g. The total mass of alkali is 32 + 20 = 52 g. The mass of the solution is 160 + 40 = 200 g. The mass fraction of alkali is 52 / 200 = 0.26 or 26%.

2. The reaction between the solutions of sodium phosphate and calcium nitrate is a double displacement reaction, where the cations and anions of the reactants exchange places and form new compounds. The reaction is also irreversible, because one of the products, calcium phosphate, is insoluble in water and precipitates out of the solution. The equation for the reaction is:

3Na3PO4(aq) + 2Ca(NO3)2(aq) → Ca3(PO4)2(s) + 6NaNO3(aq)

The two types of reaction that can be applied to this reaction are exchange and irreversible.