How to Determine Mole Fraction and Mass Percent from Osmotic Pressure Data?

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Discussion Overview

The discussion revolves around calculating mole fraction and mass percent composition from osmotic pressure data involving a mixture of sucrose, MgSO4, and KNO3 dissolved in water. The context includes understanding the implications of weight/volume% and weight/weight% in the problem.

Discussion Character

  • Homework-related
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant successfully calculated the molarity of the solution but expressed uncertainty about the next steps and the meanings of weight/volume% and weight/weight%.
  • Another participant questioned the interpretation of the weight/volume% and expressed confusion about its meaning.
  • A participant mentioned that multiplying the given percentage by 100 would yield the total mass of the mixture, but expressed doubt about this claim.
  • A further reply challenged the idea that multiplying by 100 gives the total mass, using the example of sulfuric acid to illustrate that percentages depend on the context of the measurement.

Areas of Agreement / Disagreement

Participants do not appear to reach consensus on the interpretation of weight/volume% and weight/weight%, and there are conflicting views on how to derive the total mass from the given percentages.

Contextual Notes

The discussion highlights potential limitations in understanding the definitions and implications of weight/volume% and weight/weight%, as well as the need for clarity on the context of mass measurements.

Mia Vel
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Homework Statement


When 0.32 weight/volume% of sucrose, MgSO4 and KNO3 mixture is dissolved in 997 g of H2O, the osmotic pressure at 25 deg Celsius is 1.25 atm. Calculate the mole fraction and mass percent composition of the original mixture if it contains 15% weight/weight KNO3.

2. Homework Equations

Osmotic pressure= Molarity x Gas constant x Temperature in Kelvin

The Attempt at a Solution


I was able to solve for the molarity of the solution. After it, I don't know what to do next. Can someone please teach me what the next step is and what is the role(meaning) of weight/volume % and weight/weight % in the problem? Thank you in advance. :)
 
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Mia Vel said:
When 0.32 weight/volume% of sucrose, MgSO4 and KNO3 mixture is dissolved

I have no idea what it means.
 
My friend told me that when you multiply the given percentage by 100, you will get the total mass of the mixture. I am just not sure whether I should believe him or not.
 
Mia Vel said:
My friend told me that when you multiply the given percentage by 100, you will get the total mass of the mixture.

Doesn't sound correct to me. 30% sulfuric acid doesn't always weight 3000 (and 3000 of what? stones? grams? ounces? pounds?).
 

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