Question

Помогите пожалуйста решить задачу на растворы. Дано:m(KCl) 50г.Масса воды 200г.плотность 1,0необходимо найти массовую долю растворённого вещества %. Кол-во растворённого вещества в моль.Молярная концентрация раствора моль/л. Массу раствора. Желательно записать полное решение этой задачи, а не только ответ. Заранее спасибо.

Answer 1

     
дано :                                   Решение :

m(KCl)=50г                       200г+50г = 250г весь раствор

m(H2O) =200г                    250гр р-ра __100%

Найти W (KCl)-?                  50гр KCl ____x%

n (KCl) -?                                 x =( 50грх 100 )/ 200 =20%

  М(KCl)=74.5гр                           W ( KCl) = 20%

                                                   n( KCl)=(50гр х1м)/ 74,5гр=0.67 моль

Answer 2

Solving the Solution Problem

To solve this problem, we need to find the mass fraction of the dissolved substance, the amount of the dissolved substance in moles, the molar concentration of the solution, and the mass of the solution.

Given: - Mass of KCl (m) = 50g - Mass of water = 200g - Density = 1.0 g/mL

Mass Fraction of the Dissolved Substance

The mass fraction (w) of the dissolved substance can be calculated using the formula:

w = (mass of solute / total mass of solution) x 100%

Substituting the given values: w = (50g / (50g + 200g)) x 100%

Calculating: w = (50g / 250g) x 100% = 20%

So, the mass fraction of the dissolved substance is 20%.

Amount of the Dissolved Substance in Moles

To find the amount of the dissolved substance in moles, we can use the formula:

moles = mass / molar mass

The molar mass of KCl is approximately 74.55 g/mol.

Substituting the given values: moles = 50g / 74.55 g/mol ≈ 0.67 moles

So, the amount of the dissolved substance in moles is approximately 0.67 moles.

Molar Concentration of the Solution

The molar concentration (M) of the solution can be calculated using the formula:

M = moles of solute / volume of solution in liters

Given that the mass of water is 200g and the density is 1.0 g/mL, we can calculate the volume of the solution.

Volume of solution = mass / density = 200g / 1.0 g/mL = 200 mL = 0.2 L

Substituting the given values: M = 0.67 moles / 0.2 L ≈ 3.35 mol/L

So, the molar concentration of the solution is approximately 3.35 mol/L.

Mass of the Solution

The mass of the solution is simply the sum of the mass of the solute and the mass of the solvent:

Mass of solution = mass of solute + mass of solvent = 50g + 200g = 250g

So, the mass of the solution is 250g.

Conclusion

In conclusion, the mass fraction of the dissolved substance is 20%, the amount of the dissolved substance in moles is approximately 0.67 moles, the molar concentration of the solution is approximately 3.35 mol/L, and the mass of the solution is 250g.