A solution containing 4.5mM of `Cr_(2)O_(7)^(2-)` and 15mM of `Cr^(3+)` shows a pH of 2.0. Calculate the potential of half reaction. (Standardd potential of the reaction `Cr_(2)O_(7)^(2-)rarrCr^(2+)` is 1.33 V)

A solution containing 4.5mM of `Cr_(2)O_(7)^(2-)` and 15mM of `Cr^(3+)

1.	A solution containing 4.5mM of `Cr_(2)O_(7)^(2-)` and 15mM of `Cr^(3+)` shows a pH of 2.0. Calculate the potential of half reaction. (Standardd potential of the reaction `Cr_(2)O_(7)^(2-)rarrCr^(2+)` is 1.33 V)
Answer» We know, `Cr_(2)O_(7)^(2-)+14H^(+)+6e^(-)rarr 2Cr^(3+)+7H_(2)O` `E=E_(Cr_(2)^(6+)//Cr^(3+))^(@)+(0.059)/(6)"log"([Cr_(2)O_(7)^(2-)][H^(+)]^(14))/([Cr^(3+)]^(2))` `E=1.33+(0.059)/(6)"log"([(4.5)/(1000)]xx[10^(-2)]^(14))/([(15)/(1000)]^(2))` `=1.33+(0.059)/(6)log 20xx10^(-28)` `=1.33+(0.059)/(6)[log 20-28log 10]` `=1.33+(0.059)/(6)[1.3010-28]` `=1.33-0.26=1.07V`

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A solution containing 4.5mM of `Cr_(2)O_(7)^(2-)` and 15mM of `Cr^(3+)` shows a pH of 2.0. Calculate the potential of half reaction. (Standardd potential of the reaction `Cr_(2)O_(7)^(2-)rarrCr^(2+)` is 1.33 V)

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