Question

Correct order of bond length in so3-², so4-² and so3

Answer 1

Answer: SO3, SO4-2 & SO3-2

Explanation: SO3 molecule contains 6sigma bonds and π bonds to the three O atoms. The average bond order of an S-O bond becomes 6/3=2.

In SO3-2 ion, there is a total of four sigma bonds and π bonds to the three O atoms. Therefore, the bond order of S-O bond becomes 4/3= 1.33.

In SO4-2 ion, the bond order is 1.5.

Since bond length decreases as bond order increases, SO3 have a shorter bond length.

Answer 2

we have to arrange in other of SO₃²¯, SO₄²¯ and SO₃ in bond length.

we know, bond order is inversely proportional to bond length. and bond order depends on σ - bonds and π - bonds.

i.e., bond order = 1 + π/σ

see figure here structures of all given species are given.

for SO₃²¯ : there are three σ - bonds and one π - bond. so, bond order = 1 + 1/3 = 1.33

for SO₄²¯ : there are two π - bonds and four σ - bonds. so, bond order = 1 + 2/4 = 1.5

for SO₃ : there are three π - bonds and three σ - bonds. so, bond order = 1 + 3/3 = 2

correct order of bond order : 1.33 < 1.5 < 2

i.e., bond order of SO₃²¯ < bond order of SO₄²¯ < bond order of SO₃

so bond length SO₃²¯ > bond length of SO₄²¯ > bond length of SO₃

Therefore correct order of bond length is SO₃²¯ > SO₄²¯ > SO₃