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What is the value of n in the following half equation, Cr(OH) 4 −   +   OH − → CrO 4 2 −   +   H 2 O   +   ne −   ?

Options

  1. A3
  2. B6
  3. C5
  4. D2

Correct answer

A. 3

Step-by-step solution

C r ( O H ) 4 - + O H - → C r O 4 2 - + H 2 O To balance H and O atoms, add 3 H 2 O to R.H.S. and 30 H ⊖ to the L.H.S. we have, C r ( O H ) 4 - + 4 O H - → C r O 4 2 - + 4 H 2 O To balance charge, add 3 e - to the R.H.S. we have C r ( O H ) 4 - + 4 O H - → C r O 4 2 - + 4 H 2 O + 3 e -

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