Question

9,8 g amestec echimolecular de propena si 1-butena see barboteaza intr-o sol. acidulata de K2Cr2O7.Referitor la asta care sunt corecte ?
a.amestecul de alchene decoloreaza 3,33 l sol.acidulata de K2Cr2O7 de concentratie 0,1 molar
b.se degaja 4,48 l CO2 (c.n.)
c. amestecul final se gasesc 2 acizi carboxilici in rap. molar 1:1
d.in amestecul initial se gasesc0,2 moli alchene

Answer 1

Notez cu x-moli propena si butena

42x+56x=98
x=0,1 moli
a. adevarat
C=C-C + 5{0} ---->CO2 + H20 + C-COOH
0,1...........0,5

C=C-C-C + 5{O} ----> CO2+ H2O + C-C-COOH
0,1..............0.5

AVEM in final 0,5+0,5=1 mol de oxigen
     1..............................................................................3
K2Cr2O7 + 4H2SO4 ---->K2SO4 + Cr2(SO4)3 + 4H2O + 3{O}
      x.............................................................................1

x=1/3 moli
CM=n/Vs
V=n/Cm=1/3/0,1=3,33 litri solutie K2Cr2O7

B. adevarat
cf. reactiilor, se degaja 0,1+0,1 moli CO2=0,2
1mol.........22,4
0,2............x=4,48 litri CO2

c. adevarat
amestecul final contine acid acetic si acid propanoic
0,1 moli acid acetic: 0,1 moli acid propanoic=1:1

d. adevarat
in amestecul initial sunt 0,1 moli propena si 0,1 moli 1-butena
inseamna 0,2 moli alchene