Question

1.Se considera alcena A cu denumirea: 4-metil-2-hexenă.
a)sa se scrie formula plana B a acestei alchene
b) Se considera formula plana care indeplineste urmatoarele conditii:
-au aceeasi catena ca si formula B
-corespunde formulei moleculare a alchenei A
-reprezinta un singur izomer
2.Sa se calculeze volumul de hidrocarbura C3H8, masurat la 77°C si 3,5 atm,care decoloreaza total 40mL de solutie slab bazica de KMnO4 1.5M.Sa se studieze redox acest proces

Answer 1

1. a) H3C-CH=CH-CH(CH3)-CH2-CH3

b) H3C-C(CH3)=C(CH3)-CH2-CH3

2. Cred ca ai gresit formula . Consider C3H6 hidrocarbura

VC3H6= ? (L)
t = 77°C
p = 3,5 atm
Vs = 40mL
C = 1,5M

3H3C-CH=CH2 + 2KMnO4 + 4H2O => 3CH3-CH(OH)-CH2-OH + 2KOH + 2MnO2

C(-1) -1e ---> C(0) se oxideaza (ag. red) |3
C(-2) -1e ---> C(-1) se oxideaza (ag.red) |3
Mn(+7) +3e ---> Mn(+4) se reduce (ag.ox) |2

C = n/Vs = > n = 1,5×40×10^-3 = 0,06 moli

3 moli C3H6..........2 moli KMnO4
x moli C3H6............0,06 moli KMnO4

x = 0,09 moli C3H6

pV = nRT => V = nRT/p = 0,09×0,082×350/3,5 = 0,738 L C3H6 = 738mL