Alkanes exam q Flashcards
(16 cards)
Which is a propagation step in the chlorination of methane?
A H● + Cl2 → HCl + Cl●
B Cl● + CH4 → CH3Cl + H●
C ● CH3 + Cl● → CH3Cl
D ● CH3 + Cl2 → CH3Cl + Cl●
D
Which statement is not correct about the pollutant sulfur dioxide?
A It can be removed from car exhaust gases by a
catalytic converter.
B It can be removed from power station flue gases by
reaction with calcium oxide.
C It can cause respiratory problems.
D It can cause acid rain.
A
Which statement is correct about thermal cracking?
A A pressure between 100 and 200 kPa
is used.
B Aromatic hydrocarbons are the major
products.
C C–C bonds are broken.
D Zeolite catalysts are used.
C
An excess of methane reacts with chlorine in the presence of ultraviolet
radiation.
What are the main products of this reaction?
A CCl4 and H2
B CCl4 and HCl
C CH3Cl and H2
D CH3Cl and HCl
D
The petrol fraction from crude oil contains octane (C8H18).
Give an equation for the complete combustion of octane 1 mark
C8H18 + 12.5 O2 → 8 CO2 + 9 H2O
Give an equation for a reaction that removes nitrogen monoxide in a catalytic converter. 1 mark
2NO + 2CO= N2+ 2CO2
Which equation represents a propagation step?
A CH2Cl + Cl → CH2Cl2
B CH3 + CH3 → C2H6
C Cl2 → Cl + Cl
D CH3Cl + Cl* → *CH2Cl + HCl
D
Which statement is correct about the fractional distillation of crude oil?
A A zeolite catalyst is used.
B Each fraction contains a mixture of hydrocarbons.
C Gaseous fractions are formed by breaking covalent
bonds.
D The fractionating column is hottest at the top.
B
Write an equation for the complete combustion of propane in oxygen.
C3H8 + 5O2 ⟶ 3CO2 + 4H2O
Suggest one reason, other than the use of mean bond enthalpies, why a
value for the enthalpy of combustion of a liquid alkane is different from the
value obtained using the expression in part (b)
- alkane is not gaseous or
- equation relates to gaseous alkanes or
- it takes energy to convert it into a gas or
- that water / alkane / substances are gaseous in calculations using
bond enthalpies
Which equation is a propagation step in the conversion of trichloromethane into
tetrachloromethane by reaction with chlorine in the presence of ultraviolet light?
A CHCl3 + Cl2 ⟶ CCl4 + HCl
B ●CCl3 + ●Cl ⟶ CCl4
C CHCl3 + ●Cl ⟶ CCl4 + ●H
D ●CCl3 + Cl2 ⟶ CCl4 + ●Cl
D
Which catalyst is used in the catalytic cracking of alkanes?
A Concentrated phosphoric acid
B Iron
C Nickel
D Zeolite
D
Which correctly represents an incomplete combustion of pentane?
A C5H12 + 8O2 ⟶ 5CO2 + 6H2O
B C5H12 + 8O2 ⟶ 4CO + CO2 + 6H2O
C C5H12 + 6O2 ⟶ 4CO + CO2 + 6H2O
D C5H12 + 5O2 ⟶ 4CO + CO2 + 4H2O + 2H2
C
Which species is produced in a propagation step during the reaction of propane
with an excess of chlorine in the presence of UV light?
A H*
B C3H5Cl
C C3H6CL2
D C6H14
C
Which of these substances does not contribute to the greenhouse effect?
A Unburned hydrocarbons.
B Carbon dioxide.
C Water vapour.
D Nitrogen.
D
