Question

How would you expect charge neutrality to be maintained in

(a) TiO1.25

(b) ZrO2 doped with 10% of CaO

Answer 1

(1)

Generally the charge of Ti is here is +2. But inorder to balance the charge, some of the Ti are present in state of +4

example: 4 sets of TiO_1.25 gives 4 Ti and 5 O .

Charge of 5 O = 5x-2 = -10

Charge of Ti is balanced by = 3 atoms x 2 + 1 atom x 4 == 10

In this manner charge is balanced.

(b)

Here for 100 moles of ZrO2 , 10 moles are doped with CaO, the total charge lost by ZrO2 is exactly balanced by adding CaO .

Molar mass of ZrO2 is 123.8 g/mol and molar mass of CaO = 56 g/mol

1 mole of ZrO2 is balanced by 123.8/56 == 2.21 moles of CaO.