Question

Ce masa de K2O trebuie dizolvata in solutia de KOH cu volumul de 120cm^3 , partea de masa 15% , densitatea 1,12g/cm^3 pentru a obtine solutie de 25% . Dau 100pct

Answer 1

md = ? K₂O

Vsi = 120cm³ sol. KOH
Ci = 15%
ρ = 1,12g/cm³
Cfinal = 25%

ρ = msi/Vs ⇒ msi = ρ×Vs = 1,12×120 = 134,4g sol. KOH

Ci = mdi/msi×100 ⇒ mdi = Ci×msi/100 = 15×134,4/100 = 20,16g KOH

Cfinal = (mdi+md adaugat)/(msi+md adaugat) ×100 ⇔ 25 = (20,16+md ad)/(134,4+md ad)×100 ⇔ 3360+25md ad = 2016+100md ad ⇔ 75md ad = 1344 ⇒ md adauat = 17,92g K₂O