What Is the Mass Percent Concentration of CaCl₂ in the Solution?

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SUMMARY

The discussion focuses on calculating the mass percent concentration of CaCl₂ in an aqueous solution using vapor pressure data. The vapor pressure of the CaCl₂ solution is 80.8 mmHg, while the vapor pressure of pure water at 50°C is 92.6 mmHg. Participants reference Raoult's Law to relate the vapor pressures to mole fractions, emphasizing the need to account for the dissociation of CaCl₂ into its constituent ions. The formula for mass percent concentration is confirmed as mass solute divided by mass solution.

PREREQUISITES
  • Understanding of Raoult's Law
  • Knowledge of vapor pressure concepts
  • Familiarity with molar mass calculations
  • Basic principles of solution chemistry
NEXT STEPS
  • Study Raoult's Law in detail
  • Learn about colligative properties of solutions
  • Explore the dissociation of ionic compounds in solutions
  • Practice calculating mass percent concentration with different solutes
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Chemistry students, educators, and professionals involved in solution chemistry and physical chemistry calculations.

blueskadoo42
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% by mass concentration

Homework Statement



An aqueous CaCL2 solution has a vapor pressure of 80.8mmHG at 50 degree C . The vapor pressure of pure water at this temperature is 92.6 mmHG .

What is the concentration of CaCl2 in mass percent?

Homework Equations



% by mass = mass solute/mass solution.

The Attempt at a Solution



I tried converting the pressure into moles then dividing the moles of CaCl2 by the total moles. I am pretty stuck..

Thanks
Skadoo!
 
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Do you know Raoult's law?
 


yeah i do. p = pa*xa+pb*xb correct? not sure how to solve for the x's...
 


xa+xb=1
 


alright knowing this, i use 'a' as the vap press for cacl2 and 'b' for vap press of water? then use molecular weights to to solve for total mass of solution..?
 


Sounds OK. Don't forget CaCl2 is dissociated.
 


ah right, almost forgot. Ill give this a run thanks.
 

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