NEET-XI-Chemistry

01: Redox Reactions

  • #1
    Assign oxidation numbers to the underlined elements in each of the following species:
    (a) NaH2PO4 (b) NaHSO4 (c) H4P2O7 (d) K2MnO4
    (e) CaO2 (f) NaBH4 (g) H2S2O7 (h) KAl(SO4)2.12 H2O
    Ans : null (a)

    Let the oxidation number of P be x.

    We know that,

    Oxidation number of Na = +1

    Oxidation number of H = +1

    Oxidation number of O = -2



    Then, we have



    Hence, the oxidation number of P is +5.
    (b)



    Then, we have



    Hence, the oxidation number of S is + 6.
    (c)



    Then, we have



    Hence, the oxidation number of P is + 5.
    (d)



    Then, we have



    Hence, the oxidation number of Mn is + 6.
    (e)



    Then, we have



    Hence, the oxidation number of O is - 1.
    (f)



    Then, we have



    Hence, the oxidation number of B is + 3.
    (g)



    Then, we have



    Hence, the oxidation number of S is + 6.
    (h)



    Then, we have



    Or,

    We can ignore the water molecule as it is a neutral molecule. Then, the sum of the oxidation numbers of all atoms of the water molecule may be taken as zero. Therefore, after ignoring the water molecule, we have



    Hence, the oxidation number of S is + 6.
  • #1-a
    NaH2PO4
    Ans :

    Let the oxidation number of P be x.

    We know that,

    Oxidation number of Na = +1

    Oxidation number of H = +1

    Oxidation number of O = -2



    Then, we have



    Hence, the oxidation number of P is +5.
  • #1-b
    NaHSO4
    Ans :



    Then, we have



    Hence, the oxidation number of S is + 6.
  • #1-c
    H4P2O7
    Ans :



    Then, we have



    Hence, the oxidation number of P is + 5.
  • #1-d
    K2MnO4
    Ans :



    Then, we have



    Hence, the oxidation number of Mn is + 6.
  • #1-e
    CaO2
    Ans :



    Then, we have



    Hence, the oxidation number of O is - 1.
  • #1-f
    NaBH4
    Ans :



    Then, we have



    Hence, the oxidation number of B is + 3.
  • #1-g
    H2S2O7
    Ans :



    Then, we have



    Hence, the oxidation number of S is + 6.
  • #1-h
    KAl(SO4)2.12 H2O
    Ans :



    Then, we have



    Or,

    We can ignore the water molecule as it is a neutral molecule. Then, the sum of the oxidation numbers of all atoms of the water molecule may be taken as zero. Therefore, after ignoring the water molecule, we have



    Hence, the oxidation number of S is + 6.