Sarthaks Test
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A student titrated a mixture of NaHCO3 and Na2CO3 against a standard solution of HCI. He pipetted out a certain volume of mixture and added phenolphthalein indicator. The pink solution changed to colourless after addition of x mL of HCI. To the same solution he added methyl orange indicator and continued the titration. The end point with methyl orange indicator was obtained after addition of y mL HCI. The volume of HCI required for complete neutralization of Na2CO3 is _________ . 

(a) 2 x 

(b) x/2 

(c) y 

d) y - x

1 Answer

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Best answer

Correct option: (a) 2 x


In presence of phenolphthalein indicator, equivalents of HCl = 1/2  equivalents of Na2O3.

So 1 eq. of Na2CO3 required = 2x ml of HCl.

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