Question

К 300 мл раствора гидроксид калия с плотностью 1.2 г/см и массовой доля 0,2 прибавили 40 г гидроксида калия. определить массовую долю KOH в новом растворе

Answer 1

В первом растворе: m(р-ра)= 300*1,2= 360 г
m(KOH)= 360*0.2=72 г
Второй раствор: m(р-ра)= 360 +40= 400 г
m(KOH)=72 + 40=112 г
ω(KOH)=112/400= 0,28

Answer 2

Calculation of Mass Fraction of KOH in the New Solution

To determine the mass fraction of KOH in the new solution, we need to consider the initial solution and the amount of KOH added.

Given: - Initial solution volume: 300 mL - Density of the initial solution: 1.2 g/cm³ - Mass fraction of KOH in the initial solution: 0.2 - Amount of KOH added: 40 g

To calculate the mass fraction of KOH in the new solution, we can follow these steps:

1. Calculate the mass of the initial solution: - Mass = Volume × Density - Mass = 300 mL × 1.2 g/cm³ = 360 g

2. Calculate the mass of KOH in the initial solution: - Mass of KOH = Mass of the initial solution × Mass fraction of KOH - Mass of KOH = 360 g × 0.2 = 72 g

3. Calculate the total mass of the new solution: - Total mass = Mass of the initial solution + Mass of KOH added - Total mass = 360 g + 40 g = 400 g

4. Calculate the mass fraction of KOH in the new solution: - Mass fraction of KOH = Mass of KOH / Total mass - Mass fraction of KOH = 72 g / 400 g = 0.18

Therefore, the mass fraction of KOH in the new solution is 0.18.

Please note that the search results provided by You.com did not contain relevant information for this specific calculation. The calculation was performed based on the given information and general knowledge of solution preparation.