10.2 Quiz #3 (halogenoalkanes & benzene)

Which factors help to explain why halogenoalkanes are generally more reactive than alkanes?

I. The molecules of halogenoalkanes are more polar than molecules of alkanes.

II. All C-halogen bonds are weaker than C-C and C-H bonds.

III. All the halogens are more electronegative than hydrogen and carbon.

• I and III only

• II and III only

• I, II and III

• I and II only

Methane (boiling point -161°C) and tetrafluoromethane (boiling point -128°C) are both greenhouse gases. The C-H bond enthalpy is 414 kJ mol^-1 and the C-F bond enthalpy is 492 kJ mol^-1. Which statements about methane and tetrafluoromethane are correct?

I. The molecules of both methane and tetrafluoromethane have a tetrahedral structure.

II. Methane is more reactive chemically than tetrafluoromethane.

III. Tetrafluoromethane is considerably more polar than methane.

• I, II and III

• II and III only

• I and III only

• I and II only

Which reagents can react together to give 1-chlorobutane?

• but-2-ene and hydrogen chloride

• butane and chlorine in UV light

• but-1-ene and chlorine

• butane and hydrochloric acid

Which reactions produce butan-2-ol?

I. warming 2-iodobutane with sodium hydroxide solution

II. shining ultraviolet light on a mixture of butane and water

III. heating but-2-ene with steam in the presence of an acid catalyst

• I and III only

• I and II only

• II and III only

• I, II and III

Which statement explains why halogenoalkanes react with nucleophiles?

• The bond between carbon and the halogen in all halogenoalkanes is ionic so nucleophiles are attracted to the positive carbon ion.

• The small atomic radius of a carbon atom enables the six protons in its nucleus to attract nucleophiles.

• The carbon atom bonded to the halogen atom has a vacant orbital which can accept a pair of electrons.

• Because halogens are more electronegative than carbon they attract the bonding pair of electrons more strongly making the carbon atom electron deficient with a small positive charge, δ⁺.

Which is a secondary halogenoalkane?

• 2-iodobutane

• 1-chloropropane

• 2-chloro-2-methylpropane

• 1,2 dibromoethane

What will be the organic product from the reaction between warm dilute aqueous sodium hydroxide solution and 1-bromobutane?

• but-2-ene

• but-1-ene

• butan-1-ol

• butan-2-ol

Which reagent cannot act as a nucleophile?

• the hydroxide ion, OH^-

• water, H₂O

• methane, CH₄

• ammonia, NH₃

Benzene, C₆H₆, can react with hydrogen at 180°C in the presence of a nickel catalyst to form cyclohexane, C₆H₁₂. Which terms can be used to describe what happens to benzene in this reaction?

I. reduction

II. hydrogenation

III. addition

• I and II only

• II and III only

• I, II and III

• I and III only

Benzene can react with chlorine in the presence of aluminum chloride to form chlorobenzene.

Which terms can be used to describe what happens to benzene in this reaction?

I. reduction

II. substitution

III. chlorination

• II and III only

• I, II and III

• I and III only

• I and II only