solutia finala : ms = 200g c = 50% ⇒ mNaOH = 100g mH2O = 100g
Na+ H2O ⇒ NaOH + 1/2H2↑
nNa = nH2O = nNaOH = 100/40 = 2,5 moli mNa = 2,5·23 = 57,5g
mH2O (din reactie) = 2,5·18 = 45g
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57,5 gNa + 45gH2O = 2,5·40 = 100g NaOH + (2,5 ·1/2· 2 =2,5gH2)
+ 100gH2O
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mH2O necesara = 145g