Question

Из раствора массой 700г с массовой долей нитрата калия15% выпариванием удалили 400г воды. массовая доля в % равна 357017,552.5

Answer 1

М р-ра2= 700г-400г=300г
м в-ва = м р-ра 1 * ω/100%= 700г * 15%/100%=105г
ω м в-а / м р-ра*100% = 105г/300г*100%= 35%

Answer 2

Solution:

To find the mass fraction of potassium nitrate after the evaporation, we can use the formula:

Mass fraction = (mass of solute / total mass of solution) * 100

Given: - Initial mass of the solution (before evaporation) = 700g - Mass fraction of potassium nitrate before evaporation = 15% - Mass of water removed by evaporation = 400g

First, we can calculate the initial mass of potassium nitrate in the solution: Initial mass of potassium nitrate = Initial mass of solution * Mass fraction of potassium nitrate Initial mass of potassium nitrate = 700g * 15%

Now, we can calculate the final mass of the solution after evaporation: Final mass of solution = Initial mass of solution - Mass of water removed Final mass of solution = 700g - 400g

Next, we can calculate the mass fraction of potassium nitrate after evaporation: Mass fraction after evaporation = (Mass of potassium nitrate after evaporation / Final mass of solution) * 100

Let's calculate the values step by step.

Calculations:

1. Initial mass of potassium nitrate: Initial mass of potassium nitrate = 700g * 15% Initial mass of potassium nitrate = 700g * 0.15 Initial mass of potassium nitrate = 105g

2. Final mass of the solution after evaporation: Final mass of solution = 700g - 400g Final mass of solution = 300g

3. Mass fraction of potassium nitrate after evaporation: Mass fraction after evaporation = (105g / 300g) * 100 Mass fraction after evaporation = (105 / 300) * 100 Mass fraction after evaporation ≈ 35%

Answer:

The mass fraction of potassium nitrate after the evaporation is approximately 35%.