Question

`10g` of a mixture of `BaO` and `CaO` requires `100cm^(3)` of `2.5m HCl` of react competely. The percentage of calcium oxide in the mixture is approximately
(given, molar mass of `BaO=153`)
A. `52.6`
B. `55.1`
C. `44.9`
D. `47.4`

Answer 1

Correct Answer - A
Let, mass of CaO = x g
`therefoer ` Mass of `BaO = (10 - x) ` g
Again, equivalent mass of BaO
`=("molar mass")/2 = 153/2 = 76.5`
`therefore` Number of mol of `BaO = (10-x)/76.5`
and equivalent mass of `CaO= 56/2 = 28`
`therefore` Number of mol of `CaO = x/28`
`therefore ` Moles of solute `= (2.5 xx 100)/ 1000 = 0.25`
`therefore ` For complete neutralisation (reaction), moles of BaO
and Cao = moles of HCl (solute)
`therefore x/28 + (10-x)/76.5 = 0.25`
or `76.5 x + 28(10-x) = 0.25 xx 28 xx 76.5`
or `48.5 x = 255.5`
or ` x=(255.5)/48.5=5.46 `
`therefore` Percentage of `CaO=5.26/10 xx 100 = 52. 6%`