Question

ПОЖАЛУЙСТА . ОЧЕНЬ СРОЧНО )450 г 20% раствора хлорида натрия при охлаждении теряет 50 г вещества . Найдите массовую долю вещества в охлажденном растворе .

Answer 1

M(раст.в-ва NaCl)=450*0.2=90 г
m2(раст в-ва NaCl)=90-50=40г
m2(р-ра NaCl)=450-50=400г
массовая доля(NaCl)=m2(раст в-ва NaCl)/m2(р-ра NaCl)=40/400=0.1 или 10%

Answer 2

Calculation of Mass Fraction in the Cooled Sodium Chloride Solution

To find the mass fraction of the substance in the cooled solution, we need to calculate the initial mass of the solution and the mass of the substance remaining after cooling.

Given information: - Initial mass of the solution: 450 g - Percentage concentration of the sodium chloride solution: 20% - Mass of the substance lost during cooling: 50 g

To calculate the initial mass of the substance in the solution, we can use the percentage concentration. The percentage concentration represents the mass of the solute (in this case, sodium chloride) divided by the total mass of the solution, multiplied by 100.

Let's calculate the initial mass of the substance in the solution:

Step 1: Convert the percentage concentration to a decimal fraction by dividing it by 100. 20% = 0.20

Step 2: Calculate the initial mass of the substance in the solution by multiplying the decimal fraction by the total mass of the solution. Initial mass of the substance = 0.20 * 450 g = 90 g

Therefore, the initial mass of the substance in the solution is 90 g.

Now, let's calculate the mass fraction of the substance in the cooled solution.

Step 3: Calculate the final mass of the solution after cooling by subtracting the mass of the substance lost during cooling from the initial mass of the solution. Final mass of the solution = Initial mass of the solution - Mass of substance lost during cooling Final mass of the solution = 450 g - 50 g = 400 g

Step 4: Calculate the mass fraction of the substance in the cooled solution by dividing the mass of the substance remaining after cooling by the final mass of the solution, multiplied by 100. Mass fraction of the substance = (Mass of substance remaining after cooling / Final mass of the solution) * 100 Mass fraction of the substance = (400 g / 400 g) * 100 = 100%

Therefore, the mass fraction of the substance in the cooled sodium chloride solution is 100%.

Please note that the calculations provided above are based on the given information and assumptions. If there are any additional factors or details that need to be considered, please provide them for a more accurate calculation.