Question

4.56 Ce volum de solutie K2Cr2O7 2 N este necesar pentru a obtine 9 g acid oxalic prin oxidarea a 2, 4 hexadienei :
a.400ml
b.800 ml
c.1000ml
d.1200ml
e.1600ml

raspuns corect:b

Answer 1

intai sa stabilim Eg=MK2Cr2O7/nr.e-schimbati
MK2Cr2O7=294g/mol
Eg=294/6=49g, 6 se determina din ecuatia REDOX (K2Cr2O7+ 4H2SO4 -> K2SO4 + Cr2(SO4)3 + 4H2O + 3[O])
=> Cn=2*49g/l=98g/l=0,333M (n=98/294=0,33moli)
.........................................8moli.........90g
CH3-CH=CH-CH=CH-CH3 + 8[O] -> HOOC-COOH + 2CH3-COOH
........................................0,8moli........9g
1mol........................................................................3moli
K2Cr2O7+ 4H2SO4 -> K2SO4 + Cr2(SO4)3 + 4H2O + 3[O]
0,266moli.................................................................0,8moli
Vs=n/Cm=0,266/0,33=0,8l=800ml solutie K2Cr2O7 2N