Organic Chemistry - Module 1

Question 1

What is the difference between a saturated and unsaturated hydrocarbon?

Answer 1

An unsaturated hydrocarbon contains at least one carbon-carbon double bond.

Question 2

What are the prefixes for halogenoalkanes?

Answer 2

Fluoro-, Chloro-, Bromo-, or Iodo-.

Question 3

What is the empirical formula of a compound?

Answer 3

The simplest whole-number ratio of atoms of each element present in the compound.

Question 4

How would you calculate the empirical formula for a hydrocarbon that contains 85.63% carbon and 14.37% hydrogen?

Answer 4

1. 100.0g of the compound contains 85.63g of C and 14.37g of H
2. Divide the mass of the elements by their molar mass:
3. 63/12.0 = 7.14
4. 37/1.0 = 14.37
5. Divide by the smallest number (7.14)
6. 14:14.37
   1: 2

Empirical Formula = CH₂

Question 5

What is molecular formula?

Answer 5

The actual number of atoms of each element in a molecule.

Question 6

Find the molecular formula of CH₂O which has a relative molecular mass of 60.0

Answer 6

1. CH₂O = 12.0 + 1.0 + 1.0 + 16.0 = 30.0 (relative empirical mass)
2. Relative molecular mass/relative empirical mass = 60.0/30.0 = 2
3. Molecular Formula = C₂H₄O₂

Question 7

What is the general formula for alkanes?

Answer 7

C_nH_2n+2

Question 8

What is the general formula for alkenes?

Answer 8

C_nH_2n

Question 9

What is the functional group for aldehydes?

Answer 9

Question 10

Define structural isomerism.

Answer 10

When molecules are composed of the same atoms, but are arranged in different ways.

Question 11

Define stereoisomerism.

Answer 11

What the atoms making up the isomer are joined in the same order, but have a different arrangement in space.

Question 12

What is the functional group for ketones?

Answer 12

Question 13

What criteria must a molecule satisfy to have E/Z isomerism?

Answer 13

• A carbon=carbon double bond must be present
• Each carbon in the double bond must be attached to two different groups

Question 14

Is this a cis or trans isomer?

Answer 14

Cis isomer.

Question 15

What is the functional group for carboxylic acids?

Answer 15

Question 16

Outline homolytic fission.

Answer 16

• Each bonded atom takes one of the shared pair of electrons
• Each atom then has an unpaired electron (radical)
• Two species of the same type are produced

X-Y -> X^. + Y^.

Question 17

Outline heterolytic fission.

Answer 17

• One of the bonded atoms takes both of the shared pair of electrons
• Two ions are produced
• The atom that took both shared electrons becomes an anion
• The atom the didn’t take the electrons becomes a cation

X-Y -> X⁺ + Y^-

Question 18

Define nucleophile.

Answer 18

An atom that is attracted to an electron-deficient centre or atom where it donates a pair of electrons to form a covalent bond.

Question 19

Define electrophile.

Answer 19

An atom that is attracted to an electron-rich center or atom, where it accepts a new pair of electrons to form a covalent bond.

Question 20

What happens in the initiation step for the chlorination of methane?

Answer 20

• A Cl-Cl bond is broken by homolytic fission, using energy from UV radiation
• Two chlorine radicals are formed

Question 21

What happens in the propagation steps for the chlorination of methane?

Answer 21

• What happens in the propagation steps for the chlorination of methane?

Question 22

What happens in the termination step for the chlorination of methane?

Answer 22

Two radicals combine to form a molecule. There are a number of possible combinations.

• Cl^_. + Cl^. -> Cl₂
• ^.CH₃ + ^.CH₃ -> C₂H₃
• ^.CH₃ + ^.Cl -> CH₃Cl

Question 23

What is the equation for the chlorination of methane?

Answer 23

CH₄ + Cl₂ -> CH₃Cl + HCl