Q-1. NaNO2is a basic salt (weakconjugate base of HNO2) and OH- isformed by hydrolysis of nitrite ions. Thus, 60 mL of 0.02 MNaNO2 is titrated with 0.04 M HCl. Calculate pHs in theaddition of a) 0 mL, b) 2/3 times of equivalent point volume(2/3Ve) and equivalent point volume (Ve) of HCl. Ka is5.0x10-4 for HNO2. Please use titration reaction of NaNO2 + HCl à NaCl +HNO2 |
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Q-2. A) To standardize a diluted NaOH solution,0.459 g potassium hydrogen phthalate(C8H5O4K, MA: 204 g/mol) isweighed and dissolved with pure water. Then, it is titrated withNaOH in the presence of a phenolphthalein indicator. The volume ofNaOH read from the burette is 18.5 mL when the color turns frompink to colorless, find the molarity of diluted NaOH solution?(7.5 P). Note: Stoichiometry in this titrationreaction is 1:1 for acid and base. B) a) The protein in a 1.2846g sample of an oat cereal is determined by Kjeldahl procedure. Thesample is digested with H2SO4, the resultingsolution made basic with NaOH and the produced NH3distilled into 50 mL of 0.096 M HCl. The excess HCl is then backtitrated using 23.84 mL of above standardized NaOH (If youcannot find the concentration of the above diluted NaOH solution(a), take the concentration of the diluted NaOH solution as 0.11 M.In this case, the score of the question will be 80% of the actualscore). Calculate % protein in this sample. Factor is 6.27 |
Q-3- The percentage of NaCl (58.5 g/mol) isdetermined by Mohr method in the salt solution prepared for olives.For this purpose, 7.5 mL of salt solution diluted to 100 mL withwater. Then a part of 25 mL of this diluted solution is titratedwith 2.125 % (w/v) of AgNO3 (170.0 g/mol) solution and15.5 mL of titrant is spent in the end point of indicator.Calculate percent of NaCl (w/v) in this salt solution?
A) To standardize a diluted HCl solution 0,0901g anhydrous Na2CO3 (MA:106 g/mol) is weighedand dissolved with pure water. Then, it is titrated with HCl in thepresence of a methyl orange indicator. If, the volume of HCl spentin the titration is 15.4 mL, find the molarity of diluted HClsolution?
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