Which element is oxidized in this reaction? 2CuO+C→2Cu+CO2 Which element is reduced in this reaction? 16H++2Cr2O72−+C2H5OH→4Cr3++11H2O+2CO2

Question

23372 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2017-06-11T17:13:01

The element oxidized is the one whose oxidation number INCREASES......

And thus......

$stackrel(+II)" 2CuO" +Crarr2stackrel(0)Cu+CO_2uarr$

And here while copper (as $Cu^(2+)$ ) is reduced, carbon is oxidized, $stackrel(0)Crarrstackrel(+IV)C$ .

The second reaction represents the reduction $Cr(VI+)$ to $Cr(III+)$

$Cr_2O_7^(2-)+14H^+ +6e^(-) rarr 2Cr^(3+)+7H_2O$ $(ii)$

And the oxidation of ethanol to carbon dioxide:

$H_3C-CH_2OH +H_2O rarr2CO_2+8H^(+) + 8e^(-)$ $(iii)$

i.e. $H_3stackrel(-III)C-stackrel(-I)CH_2OHrarr2stackrel(+IV)CO_2$

We takes $4xx(ii)+3xx(iii)$ to eliminate the electrons.....

$3H_3"CC"H_2OH +3H_2O +4Cr_2O_7^(2-)+56H^+ +24e^(-)rarr8Cr^(3+) + 28H_2O + 6CO_2+24H^(+) + 24e^(-)$

To give finally............

$3H_3"CC"H_2OH +4Cr_2O_7^(2-)+32H^+ rarr8Cr^(3+) + 25H_2O + 6CO_2$

$"Dichromate ion"$ is reduced to $"chromic ion"$ .........