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A sample of mixed alkali contains NaOH a...

A sample of mixed alkali contains `NaOH and Na_2 CO_3` is titrated in the following two schemes. (1) 10 mL of above mixture requires 8 mL of 0.1 N HCl by using phenolphthalein. (ii) 10 mL of above mixture requires 10 mL 0.1 N HCI by using methyl orange. What will be the ratio of the weight of NaOH and Na2CO3 in the sample mixture?

A

`1: 132`

B

`2.412`

C

`2.122`

D

`3.142 :1`

Text Solution

Verified by Experts

The correct Answer is:
A
Meq if HCI for 10 mL of mixture using phenolphthlein indicator `= 8 xx 0.1 = 0.8`
` therefore ` Meq of `NaOH +1/2 Meq ` of ` Na_2 CO_3 = 0.8`
Now Meq of HCI used for 10 mL mixture using methyl organe as indicator `=10 xx 0.1 =1`
Meq `of NaOH +Meq Of Na_2 CO_3 =1`
` therefore ` BY eqn (i ) and (ii )
Meq of ` NaOH =0.6 Meq ` of `Na_2 CO_3 = 0.4`
` (w )/( 40) xx 1000 =0.6`
` (w)/( 106 //2) xx 1000 =0.4`
wt of `NaOH = 0.024 ` wq of `Na_2 CO_3 = 0.0212`
ratio of the weight of `Na_2 CO_3 = ( 0.024 )/( 0.0212 ) = 1.132 :1`
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