When SO2 is bubbled into a beaker of acidified K2Cr2O7 solution,which of the following statements about the reaction is correct?
A. SO2 bleaches acidifed K2Cr2O7
Why this is wrong?
B.The oxidation number of Chromium changes from +6 to+2
C.The colour of the solution turns green
Why this is wrong?
D. SO2 is oxidized
SO2唔會變左SO3-2先,一次過到SO42-?
ans:D
SO2+KCr2O7
2007-02-15 5:10 am
回答 (2)
2007-02-15 6:33 am
✔ 最佳答案
A is wrong.SO2 bleaches by reduction. This is only correct when the reduced form of the dye is COLOURLESS.
However, the reduced form of dichromate is Cr3+ which is green.
So A is not correct.
B is not correct. The O.N. changes from +6 to +3
Actually i wonder why C is wrong. Prehaps you can say that in actual practical we can see "blue-green" rather than green
D is correct. SO2 is directly oxidized to SO42-
參考: My CHEM
2007-02-15 6:44 am
Actually , the redox reaction of SO2 is due to the SO3-2
Because when SO2 contact with H2O
it will form SO3-2 ions
So3-2 will be the reducing agent
so you are right ~
SO2 will first be changed into SO3-2 before redox reaction !
So the prsence of H2O in the solution is necessary for the reaction to occur!
2007-02-14 22:51:03 補充：
Overall , SO2 is oxidized~
Because when SO2 contact with H2O
it will form SO3-2 ions
So3-2 will be the reducing agent
so you are right ~
SO2 will first be changed into SO3-2 before redox reaction !
So the prsence of H2O in the solution is necessary for the reaction to occur!
2007-02-14 22:51:03 補充：
Overall , SO2 is oxidized~
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