What Is The Mass Percent?
A sample weighing 14.98g and containing a small amount of copper was treated to give a solution containing aqueous Cu^2+ ions. Sodium iodide was then added ti yield solid copper (I) iodide plus I3^- ion, and the I3^- was titrated with thiosulfate, S2O3^2-. The titration required 10.49mL of .100M Na2S2O3 for complete reaction. What is the mass percent copper in the sample? The balanced equations are…
2Cu^2+(aq)+5I^-(aq)—->2CuI(s)+I3^-(aq)
I3^-(aq)+2S2O3^2-(aq)—->3I^-(aq)+S4O6^2-(aq)
Posted on October 1, 2013, in #question and tagged 10.49mL of .100M Na2S2O3, A sample weighing 14.98g and containing, aq, Chemistry, copper, mass percent, molar concentration, question, science, Sodium iodide, The balanced equations are, What Is The Mass Percent?. Bookmark the permalink. 1 Comment.
Rant4u 
.1M(.01049L) = .001049 mol S2O3^2-
.001049mol(1mol/2mol)(2mol/1mol) = .001049mol Cu^2-
.001049mol (63.55gCu/1mol) = .06666g Cu^2-
mass % = (.06666gCu^2-/14.98g) (100) = .4450% Cu
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