To 300 grams of a potassium nitrate solution with a mass fraction of 20%, 40 grams of the same salt was added

| January 16, 2021 | education

To 300 grams of a potassium nitrate solution with a mass fraction of 20%, 40 grams of the same salt was added, which is equal to the mass fraction of potassium nitrate in the resulting solution.

KNO3 – potassium nitrate.
1) From the formula for finding the mass fraction of a substance, we express the mass of a solute. We get: mr.v-va = mr – pa * W / 100% = 300 * 20/100 = 60g.
2) Once we add salt, then both the mass of the salt and the mass of the entire solution change. We calculate the mass of the resulting solution. To do this, add the mass of the original solution with the mass of added salt: 300 + 40 = 340g.
3) The mass of the solute in the resulting solution: 40 + 60 = 100g.
4) We calculate the mass fraction of salt in the resulting solution: 100/340 * 100 = 29.2% – the answer.



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