Please help! Thanks! 1. Suppose that for the preparation of the stock solution o
ID: 972467 • Letter: P
Question
Please help! Thanks!
1. Suppose that for the preparation of the stock solution of borax, the solid borax reagent is contaminated with a water-soluble substance that does not react with hydrocholoric acid and does not have an ion in common with borax. How will this contamination affect the calculated solubility product of borax according to the Experimental procedure?
2. In the analysis of B4O5(OH)42- concentration in one of the 5-ml borax samples, suppose that the bromocresol green endpoint was surpassed. How does this affect the reported solubility product of borax at that temperature? Explain.
Explanation / Answer
1) SInce the impurity does not react with HCl or does not share a commong ion wih borax it will not have any effect on the overall solubiliyt of borax which is estimated by titration method.
2) The endpoints with respect to Bromocresol green is at pH <3.8 yellow and at pH >5.4 blue. So initially the indicator was blue in the borax solution and then became yellow in the acid. Now the pH is <3.8. The actual endpoint is around 4.8 so we have added more acid so in terms of solubility we have solubilized borax more than it is actually calculated using Ksp. So the estimated value of Ksp is higher.