Solve for K2Cr2O7 in Solution Calculation Homework

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SUMMARY

The discussion focuses on calculating the amount of potassium dichromate (K2Cr2O7) needed to saturate a solution at 20°C, given a starting concentration of 6.50% in a 350 g solution. The correct amount to be added is 18.5 g, as opposed to the incorrect calculation of 10 g. The error arose from miscalculating the existing amount of K2Cr2O7 in the solution rather than determining the additional quantity required for saturation at the specified concentration of 12.6 g per 100 g of solution.

PREREQUISITES
  • Understanding of solution concentration calculations
  • Knowledge of percentage composition in chemistry
  • Familiarity with the properties of potassium dichromate (K2Cr2O7)
  • Basic grasp of temperature effects on solubility
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  • Review calculations for solution saturation points at various temperatures
  • Study the solubility rules for potassium dichromate in different solvents
  • Learn about the implications of concentration changes on chemical reactions
  • Explore advanced topics in solution chemistry, such as colligative properties
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Chemistry students, educators, and professionals involved in laboratory work or solution preparation who need to accurately calculate solute quantities for desired concentrations.

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Homework Statement


How many grams of K2Cr2O7 (350 g 6,50%) must be added to get saturate the solution at 20C (12,6 g/100 g)?

Homework Equations



The Attempt at a Solution


350 g x 0,065 = 22,75 K2Cr2O7
I got 10 g, but it's not correct. The correct answer is 18,5 g.
 
Last edited:
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You calculated the amount of the dichromate already present, not the amount that has to be added to saturate the solution.
 

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