1. The Fe3+-ion and salicylic acid (SA) react to give a complex. The equilibrium reaction is Fe3+ + SA ⇌ FeSA3+. A volume of 20 mL of a Fe3+-solution is added to 30 mL of a salicyl... 1. The Fe3+-ion and salicylic acid (SA) react to give a complex. The equilibrium reaction is Fe3+ + SA ⇌ FeSA3+. A volume of 20 mL of a Fe3+-solution is added to 30 mL of a salicylic acid solution. Both solutions have a concentration of 5.00 × 10-4 mol L-1. At equilibrium the complex concentration ([FeSA3+]) is 1.56 × 10-4 mol L-1. Calculate the equilibrium constant (K) for the formation of the complex FeSA3+. 2. When the aforementioned solution at equilibrium is diluted 4 times it appears that [FeSA3+] is less than 1/4 × 1.56 × 10-4 mol L-1. Give an explanation for this. If you have trouble finding the answer, ask yourself if the ratio of concentrations equals K just after dilution. 3. In this practical course a stock solution of Fe3+ is available. Assume that its concentration is 8.25 × 10-4 mol L-1 Fe3+. Suppose you have to prepare 1 L of such a solution. How much (in g or mg) of the salt FeNH4(SO4)2 · 12 H2O is needed to prepare 1 L?
Understand the Problem
The image presents three chemistry problems related to equilibrium, dilution, and solution preparation. The first problem involves calculating the equilibrium constant for the formation of a complex ion. The second asks for an explanation regarding the change in complex concentration upon dilution. The third deals with determining the mass of a salt required to prepare a solution of a specific concentration.
Answer
1. K = 2.47 2. The system will shift to the left, \[FeSA3+] < 1/4 * 1.56 x 10-4 mol L-1 3. 0.404 g
- K = 2.47
- The system shifts to the left, therefore [FeSA3+] < 1/4 * 1.56 x 10-4 mol L-1
- 0.404 g of FeNH4(SO4)2 · 12 H2O is needed to prepare 1 L.
Answer for screen readers
- K = 2.47
- The system shifts to the left, therefore [FeSA3+] < 1/4 * 1.56 x 10-4 mol L-1
- 0.404 g of FeNH4(SO4)2 · 12 H2O is needed to prepare 1 L.
More Information
These calculations involve determining equilibrium concentrations, applying Le Chatelier's principle, and calculating molar mass to prepare a solution.
Tips
A common mistake is not accounting for volume changes upon mixing the two solutions when calculating initial concentrations. Also, remember to use the correct molar mass for the calculation in the third part.
Sources
- [Solved] he Fe3ion and salicylic acid SA react to give a complex The - studeersnel.nl
- 4.4: Day 30- ICE Table, Reaction Quotient, Le Châtelier's Principle - chem.libretexts.org
- 4.4 – Le Châtelier's Principle - eCampusOntario Pressbooks - ecampusontario.pressbooks.pub
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