1) Samples containing iron (II) ion can betitrated with solutions containing dic

Question

1) Samples containing iron (II) ion can betitrated with solutions containing dichromate ion under acidicconditions. Cr2O7-2+ 6Fe +2+14H+ ---> 2Cr+3+6Fe+3+7H2O a) Which ion is oxidized in thisreaction? b)Which ion is the oxidizing agent in thisreaction? c) If a 1.618g sample containing iron (II)sulfate is dissolved and requires 33.1mL of 0.0115M K2Cr2O7 solution to titrateit, what is the percent iron(II) sulfate in the sample? 1) Samples containing iron (II) ion can betitrated with solutions containing dichromate ion under acidicconditions. Cr2O7-2+ 6Fe +2+14H+ ---> 2Cr+3+6Fe+3+7H2O a) Which ion is oxidized in thisreaction? b)Which ion is the oxidizing agent in thisreaction? c) If a 1.618g sample containing iron (II)sulfate is dissolved and requires 33.1mL of 0.0115M K2Cr2O7 solution to titrateit, what is the percent iron(II) sulfate in the sample?

Explanation / Answer

Cr2O7-2 + 6Fe+2+14H+ ---> 2Cr+3+6Fe+3+7H2O in this Cr changed from +6 to +3 so decrease in oxidationstate [[reduction]] Fe changed from +2 to +3 so increase in oxidation state[[oxidation]] a)Fe+2 is Oxidized b)Oxidizing agent is the one which gets reduced i.eCr2O7-2 -------------------------------------------------------meqof K2Cr2O7 is   33.1*0.0115*6 (Normality= 6*molarity forcr in this reaction) =>meq of Fe+2 = 33.1*0.0115*6 =2.2839 => if x is the weight of Fe+2 then x/56=2.2839/1000 => x= 0.1278 g of Fe+2 => Fe+2 percentage in the sample = (0.1278/1.618)*100=7.89%

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