`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`)

Options

A. 52.6
B. 55.1
C. 44.9
D. 47.9

Answer

A

Explanation

Let mass of `CaO=xg`
`:.` Mass of `BaO=(10-x)g`
Again equivalent mass of `BaO`
`=("molar mass")/2=153/2=76.5`
`:.` Number of moles of `BaO`
`=(10-x)/76.5`
and equivalent mass of `CaO`
`=56/2=28`
`:.` Number of moles of `CaO=x/28`
from molarity
`=("moles of solute")/("volume of solution"("in"L))`
`2.5=("moles of solute")/(100/1000)`
`:.`Moles of solute `=(2.5xx100)/1000=0.25`
`:.` For complete neutralisation (reaction), moles of `BaO` and `CaO=` moles of HCl (solute)
`:.x/28+(10-x)/76.5=0.25`ltbRgt or `76.5+28(10-x)`
`=0.25xx28xx76.5`
or `48.5x=255.5`
or `x=255.5/48.5=5.26`
`:.%` of `CaO=5.26/10xx100=52.6%`