The quantity of antimony in a sample can be determined by an oxidation-reduction
ID: 969173 • Letter: T
Question
The quantity of antimony in a sample can be determined by an oxidation-reduction titration with an oxidizing agent. A 5.95-g sample of stibnite, an ore of antimony, is dissolved in hot, concentrated HCl(aq) and passed over a reducing agent so that all the antimony is in the form Sb3 (aq). The Sb3 (aq) is completely oxidized by 27.0 mL of a 0.125 M aqueous solution of KBrO3(aq). The unbalanced equation for the reaction is Br-3 + Sb3+ -----> Br- + Sb5+. Calculate the amount of the antimony in the sample and its percentage in the ore. ____?____ grams ____?____%
Explanation / Answer
balanced equation
BrO3^- + 6H^+ + 3Sb^3+ ---> Br^- + 3Sb^5+ + 3H2O
from equation
1 mol BrO3^- = 3 mol Sb^3+
No of mol of BrO3^- reacted = 27/1000*0.125 = 0.0034 mol
No of mol of sB^3+ present in sample = 0.0034*3 = 0.0102 mol
mass of Sb^3+ = 0.0102*121.76 = 1.242 grams
percentage of Sb = 1.242/5.95*100 = 20.87%
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