Question

PH = 9 объем принять за литр m(Ca(OH)2)-?

Answer 1

1)Выразим pOH:

pOH=14-9=5⇒[OH⁻]=10⁻⁵ моль/л

2)Поскольку равновесие диссоциации воды практически полностью смещено в сторону образования молекулы H₂O, то концентрацию ионов OH⁻ в растворе можно принять только исходя из диссоциации Ca(OH)₂.

Ca(OH)₂=Ca²⁺+2OH⁻

Тогда ν(Ca(OH)₂)=10⁻⁵/2 моль

Отсюда m(Ca(OH)₂)=74(г/моль)*10⁻⁵/2(моль)=37*10⁻⁵г

Answer 2

To find the molar mass of Ca(OH)2 and then calculate the mass of Ca(OH)2 needed to reach a pH of 9, we need some additional information:

1. The molarity of the Ca(OH)2 solution you are using.
2. The volume of the solution (in liters) you want to calculate the mass for.

Without this information, it's not possible to provide a specific answer. However, I can walk you through the general steps to calculate the mass of Ca(OH)2 required.

Step 1: Find the molar mass of Ca(OH)2. The molar mass of Ca(OH)2 can be calculated by adding the molar masses of its constituent elements: Ca: Atomic mass of calcium = 40.08 g/mol O: Atomic mass of oxygen = 16.00 g/mol (two oxygen atoms in Ca(OH)2) H: Atomic mass of hydrogen = 1.01 g/mol (two hydrogen atoms in Ca(OH)2)

Molar mass of Ca(OH)2 = (40.08 g/mol) + 2*(16.00 g/mol) + 2*(1.01 g/mol) = 74.16 g/mol

Step 2: Calculate the mass of Ca(OH)2 needed. To calculate the mass of Ca(OH)2 required to reach a pH of 9, we would need to know the volume of the solution you are considering (in liters) and the molarity of the Ca(OH)2 solution. The pH alone is not sufficient to determine the required mass.

If you provide the necessary additional information, I'll be happy to assist you further with the calculation.