In the study of titration of NaOH and `Na_(2)CO_(3)`. NaOH and `NaHCO_(3)`, `Na_(2)CO_(3)` and `NaHCO_(3)`, phenophthalein and methyl orange are used as indicators.
(a). When phenolphthalein is used as an indicator for the above mixture:
(i). It indicates complete neutralisation of NaOH or KOH
(ii). It indicates half neutralisation of `Na_(2)CO_(3)` because `NaHCO_(3)` is formed at the end point.
(b). When methyl orange is used as an indicator for the above mixture
(i). It indicates complete neutralisation of `NaOH` or KOH
(ii). It indicates half neutralisation of `Na_(2)CO_(3)` because `NaCl` is formed at the end point.
Q. A 10 g moxture of `NaHCO_(3)` and `KOH` is dissolved in water to make 1000 mL solution. 100 " mL of " this solution required 50 " mL of " 0.2 M HCl for complete neutralisation in the presence of phenolphthalein as indicator What is the percentage of `NaHCO_(3)` in the mixture?

Options

A. `50%`
B. `56%`
C. `44%`
D. `60%`

Answer

C

Explanation

`NaHCO_(3)overset("Phenolphthalein")to` No reaction
So, `m" Eq of "HCl=mEq KOH`
`50xx(0.2)/(100mL)`
`=50xx0.2xx(10)/(1000)mL`
`=100mEq`
`=100xx10^(-3)xx56g of KOH`
`=5.6g`
Weight of `NaHCO_(3)=(10-5.6)=4.4g`
`% of NaHCO_(3)=(4.4)/(10)xx100=44%`