Question

A solution containing Na2CO3 and NaOH requires 300ml of 0.1 N HCl using phenolpthalein as an indicator. Methyl orange is then added to the above titrated solution when a further 25ml 0f 0.2N HCl is required. the amount of NaOH present in soultion is?

Answer 1

Answer on Question #80142 - Chemistry - Physical Chemistry

Question:

A solution containing Na2CO3 and NaOH requires 300ml of 0.1 N HCl using phenolphthalein as an indicator. Methyl orange is then added to the above titrated solution when a further 25ml of 0.2N HCl is required. the amount of NaOH present in solution is?

Solution:

$\mathrm{Na_2CO_3 + 2HCl = NaCl_2 + H_2O}$

$\mathrm{n(HCl)} = \mathrm{c}^{*}\mathrm{V} = 0.1^{*}0.3 = 0.03\mathrm{mol};$

$\mathrm{n(HCl)} = \mathrm{n(NaOH)} = 0.03\mathrm{mol};$

$\mathrm{n(HCl)_2 = c^*V = 0.2^*0.025 = 0.005mol}$

$\mathrm{n(HCl)_{total}} = 0.035\mathrm{mol};$

$\mathrm{w(NaOH)} = 0.03 / 0.065 = 0.4615 = 46.15\%$ .

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