Question

un amestec format din 140 g solutie hidroxid de potasiiu 15% si 2g solutie soda caustica NaOH ,C=20% se neutralizeaza cu 40 g solutie H3PO4.
Ce concentratie wäre H3PO4

Answer 1

in 40g solutie H3PO4 se gasesc masele de acid pe care le voi calcula cu ajutorul reactiilor si a maselor de KOH siNaOH
c/100= md/ms
15/100=md/140--> md=21gKOH; Macid=98g/mol;M,KOH=56g/mol
H3PO4+3KOH--> K3PO4+3H2O
98g........3x56g
m=...........21g----> m=12,25gH3PO4

c/100=md/ms---> 20/100=md/2---> md=0,40gNaOH;M,NaOH= 40g/mol
H3PO4+3NaOH---> Na3PO4 +3H2O
98g.......3x40g
m=..........0,4---> m=0,33gH3PO4
m,acid total= 12,25+0,33--> 12.58g--> aceasta e masa dizolvata in solutie, md
c= 100md/ms--> c= 12,58x100/ 40................> calculeaza !!!!