Question

Хлорид натрия массой 32 г растворили в 125 г воды. К полученному раствору решили еще добавить 3 г соли. Вычислите массовую долю первого и второго раствора.

Answer 1

Дано:

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m1(NaCl) = 32 г

m(H2O) = 125 г

m2(NaCl) = 32 + 3 г = 35 г

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m1(р-ра) - ?

m2(р-ра) - ?

Решение:

m(р-ра) = m(в-ва) + m(воды)

w(в-ва) = m(в-ва)/m(р-ра)

m1(р-ра) = m1(NaCl) + m(H2O) = 32 г + 125 г = 157 г

m2(р-ра) = m2(NaCl) + m(H2O) = 3 г + 157 г = 160 г

w1(NaCl) = 32г/157г = 0,2038  (20,38%)

w2(NaCl) = 35г/160г = 0,2187  (21,87%)

Ответ:  20,38% и 21,87% соответственно

Answer 2

Calculation of Mass Fraction of the First Solution

To calculate the mass fraction of the first solution, we need to determine the mass of the solute (sodium chloride) and the mass of the solution (sodium chloride + water).

Given: - Mass of sodium chloride = 32 g - Mass of water = 125 g

To calculate the mass fraction of the first solution, we use the formula:

Mass Fraction = (Mass of Solute / Mass of Solution) * 100%

Substituting the given values:

Mass Fraction of the First Solution = (32 g / (32 g + 125 g)) * 100%

Simplifying the expression:

Mass Fraction of the First Solution = (32 g / 157 g) * 100%

Calculating the value:

Mass Fraction of the First Solution ≈ 20.38%

Calculation of Mass Fraction of the Second Solution

To calculate the mass fraction of the second solution, we need to determine the mass of the additional salt and the total mass of the solution after adding the salt.

Given: - Mass of additional salt = 3 g

To calculate the mass fraction of the second solution, we use the same formula as before:

Mass Fraction = (Mass of Solute / Mass of Solution) * 100%

Substituting the given values:

Mass Fraction of the Second Solution = (3 g / (32 g + 125 g + 3 g)) * 100%

Simplifying the expression:

Mass Fraction of the Second Solution = (3 g / 160 g) * 100%

Calculating the value:

Mass Fraction of the Second Solution ≈ 1.88%

Therefore, the mass fraction of the first solution is approximately 20.38%, and the mass fraction of the second solution is approximately 1.88%.