HARD
JEE Main/Advance
IMPORTANT
Earn 100

A steel sample is to be analysed for Cr and Mn simultaneously. By suitable treatment the Cr is oxidized to Cr2O72- and the Mn to MnO4-.A10.00 g sample of steel is used to produce 250.0 mL of a solution containing Cr2O72- and MnO4-.A10.00 mL portion of this solution is added to aBaCl2 solution and by proper adjustment of the acidity, the chromium is completely precipitated as BaCrO4;0.0549 g is obtained. A second 10.00 mL portion of this solution requires exactly 15.95 mL of 0.0750 M standard Fe2+ solution for its titration (in acid solution). Calculate the % of Mn and % of Cr in the steel sample.

Important Questions on Redox Reactions

HARD
JEE Main/Advance
IMPORTANT
A 1.5 g sample containing oxalic acid and some inert impurity was dissolved in enough water and volume made up to 250 mL. A 20 mL portion of this solution was then mixed with 30 mL of an alkali solution. The resulting solution was then treated with stoichiometric amount of CaCl2 just needed for precipitation of oxalate as CaC2O4. Solution was filtered off and filtrate was finally titrated against 0.1 M HCl solution. 8.0 mL of acid was required to reach the equivalence point. At last, the above neutral solution was treated with excess of AgNO3 solution and AgCl obtained was washed, dried and weighed to be 0.4305 g.De- termine mass percentage of oxalic acid in the original sample:
HARD
JEE Main/Advance
IMPORTANT
A 1 g sample containing NaOH as the only basic substance and some inert impurity was left exposed to atmosphere for a very long time so that part of NaOH got converted into Na2CO3 by absorbing CO2 from atmosphere. The resulting sample was dissolved in water and volume made upto 100 mL. A 20 mL portion of this solution required 16 mL 0.25 M HCl solution to reach the equivalence point when methyl orange was used as indicator. In a separate analysis, 20 mL portion of the same solution was taken along with phenolphthalein indicator and mixed with 50 mL of 0.1 M HCl solution. An additional 9.00 mL 0.1 M Ba(OH)2 solution was required to just restore the pink colour of solution. Determine mass percentage of NaOH in the original sample and mass percentage of Na2CO3 in the sample after exposure to atmosphere.
EASY
JEE Main/Advance
IMPORTANT

Write balanced net ionic equation for the following reactions in acidic solution.

(a) S2O32-aq +Cr2O72-aq S4O62-aq +Cr3+aq

(b) ClO3-aq +As2 S3s Cl-aq +H2AsO4-aq +HSO4-aq

(c) IO3-aq +Res ReO4-aq +I-aq

MEDIUM
JEE Main/Advance
IMPORTANT

Write balanced net ionic equations for the following reactions in basic solution :

(a) Tl2O3(s)+NH2OH(aq)TlOH(s)+N2(g)

(b) CuNH342+aq+S2O42-aqSO32-aq+Cus+NH3aq

(c) MnOH2s+MnO4-aqMnO2s

MEDIUM
JEE Main/Advance
IMPORTANT

In a quantitative determination of iron in an ore, an analyst converted 0.40 g, of the ore into its ferrous. This required 40.00 mL of 0.1 N solution of KMnO4 for titration.

(i) How many milliequivalents of KMnO4 does 40.00 mL of 0.1 N solution represent?

(ii) How many equivalents of iron were present in the sample of the ore taken for analysis?

(iii) How many grams of iron were present in the sample?

(iv) What is the percentage of iron in the ore?

(v) What is the molarity of KMnO4 solution used?

(vi) How many moles of KMnO4 were used for titration ? (Fe=56)

EASY
JEE Main/Advance
IMPORTANT
Consider the reaction H++IO4-+I-I2+H2O. Find the ratio of coefficients of IO4-,I- and I2.
EASY
JEE Main/Advance
IMPORTANT
200 mL of a solution of mixture of NaOH and Na2CO3 was first titrated with Ph and N10HCl.17.5 mL of HCl was required for end point. After this MeOH was added and 2.5 mL of same HCl was again required for next end point. Find out amounts of NaOH and Na2CO3 in the mix.
EASY
JEE Main/Advance
IMPORTANT
A solution contains Na2CO3 and NaHCO3.10 mL of this requires 2 mL of 0.1 M H2SO4 for neutralisation using Ph indicator. MeOH is then added when a further 2.5 mL of 0.2 M H2SO4 was needed. Calculate strength of Na2CO3 and NaHCO3.