Question

Sodium hydroxide can be produced by electrolysis of NaCl solution

2NaCl(aq)   +   2 H₂O(l)     à 2 NaOH(aq)    +    H₂(g)      +   Cl₂(g)     

A 100 g of 20 % aqueous solution of NaClwas used and conversion of NaCl is 90 %. Neglecting solubility of H₂ and Cl₂ in water, calculate % NaOH in the aqueous product.

use molecular balance method

Answer 1

Solution moly of = 80gm. Reaction: 2NaCl(aq) + 2 M20 (1) = 2NaOH (aq) + Hz G) + Cl2 (5) Amount of Nace in 100 gm aq. & dution = 2ogm. No of H₂O 209m 0.34188 Nace Na (: No. of moles of mass of 58.5gm/me Mol. wt No. of moles of M20 80gm 4.443mol. 189m/gmal gmol - amount output v Since conversion of Nace is only 90%, of Nace converted = 0.90 x 0.34188 - 6:379866-g mot.0.307692 gmolo Individual species molecular balance: NacL: Input + consumption. 0.34 188 god 0034188 + 0.3076929.mat. Water: Input = output t consumption Input = 4.44g.mot. Consumption 2. moles H₂O 0.307692 moles Nace 2 moles Nace oo o. 307892 gmoles H2O output 4.44- 0.3079692 gmole. = 4.1323089.moles. х 0.3076929' mol Nou NaOH : output Generation. 2 mold NaOH 2 moky Nace 0.3074929. mol. Na OH and I 0.3076929.my Nad H2 X I mol of H2 / Uz 2 moles of Noce Output = Generation =

.. Generation of H29) = 0.153846 g mol clzlg) = 0.153846g.moto : 4.13 2308 gimol x 18.99 Amount of unreacted H2O - 14 28 144 14: in product = gmal the product : 0.307692 g. mat. y 40gm Amount of NaOH in x 100 = 12.30768gm 12.30768 gm Noong mi Mass I of NaOH in the acqueous product ignoring dissolution of Hz and az 16.554 74.3815449m Ans: Percentage Haoh in aq. product = 16.551