25ml of NaHCO3& Na2CO3 is titrated with N/20 HCl soln.In phenolphthalein indicator soln.needs 20.5mlof HCl.29.5ml is added.Find strength of Na2CO3 &NAHCO3

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giorgiana1976 | College Teacher | (Level 3) Valedictorian

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Let's write the two steps of reaction of Na2CO3 with HCl

Na2CO3 + HCl -> NaHCO3 + NaCl

NaHCO3 + HCl -> H2O + CO2(g) + NaCl

The volume of HCl used to titrate each 25mL of Na2CO3 is of 50mL.

Therefore, if you want to titrate 25mL of Na2CO3, you'll have to use a volume of HCl which is twice then the volume of Na2CO3.

If you have an amount of 20.5 mL of HCl, then the amount of Na2CO3 isĀ  of 20.5/2 = 10.25 mL.