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a.FeCI_(3) is yellow in aqueous solution but nopassing H_(2)S gas, solutionrurnsgreenExample. b.Aqueous solution of K_(2)Cr_(2)O, (orange) changes to yellow .can you explain? c. Potassium permanganate in purple in colour .On adding KOH, it turn gases, What is the compound formed? d. A metailic statue under scis-rain attack turns to blushing -green colour .What can be the probable metal and salt formed ? e. Oil painting turnblackish ater some time , What is the salt formed ? Assumeoil pointcontains Pb^(2+) |
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Answer» Solution :a. `FaCI_(3)` is yellow in aqueoussolution , but on passing `H_(2)S` gas , solutionturns green , the due to formationof `FaCI_(2)` Which isgreen in colour . `UNDERSET(Yellow)(FeCI_(3)) + H_(2) rarr underset(Green)(FeCI_(2)) + 2HCI + S` b. Aqueous solution of potassium dicharomate `(K_(2)Cr_(2)O_(3))` changes to yellow due to `underset("Orange")(Cr_(2)O_(7)^(2-))+2OH^(Theta) hArr underset(Yellow)(2CrO_(4)^(2-)) +H_(2)O` c. Potassium permanganate `KMnO_(4)` reacts with `KOH` producingpotassiummanganate which is green in colour `underset("Purple")(KMnO_(4)) + KOH rarr underset("Green")(2K_(2)MnO_(4)) + H_(2)O + (1)/(2) O_(2)` d. Acid rain constitues `HNO_(2)` and `H_(2)SO_(4)` `HNO_(3)` on reaction with copper present in state oxides metails `Cu` to `Cu^(2+)` , which give a blush-green colour to the state `Cu_((s)) + HNO_(3(aq)) + 2H_((aq))^(Theta)rarr Cu_((aq))^(2+) 2NO_(2) + 2H_(2)O`.Hence metal is `Cu` and salt formed is `Cu^(2+)` e. Oil paintingturnblackish after SOMETIMES , due toreaction of `Pb^(2+)` (present in oil points) with sulphides present is atmosphere , which result in the formation of `PbS` (black in colour) `underset(("In oil paint"))(Pb^(2+)) + S^(2-) rarr underset(Black)(PbS darr)` |
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