C11 & 12 - Organic Chemistry and Alkanes Flashcards

Question

What type of bonding is present in alkanes?

Answer 1

Single covalent bonds joining the C's and H's These types of covalent bonds are called sigma bonds.

Answer 2

Is a type of covalent bond as the result of two overlapping orbitals, one from each bonding atom. The sigma bond has two electrons shared between binding atoms and is on a line directly between bonding atoms.

Answer 3

Each C atom is surrounded by 4 electron pairs in four sigma bonds. Repulsion results in a 3D tetrahedral shape around each C atom with a bond angle approx 109.5°.

Answer 4

The greater the number of atoms, the stronger the London forces between the atoms therefore more energy is required to overcome the bonds.

Answer 5

London forces act between molecules that are in close surface contact. As chain length increases, the molecules have a larger surface area so more surface contact is possible between molecules. The London forces between molecules will be greater so more energy is needed to overcome the forces.

Answer 6

Branched isomers have lower boiling points. This is because there are fewer surface points of contact between molecules of the branched alkanes so there are fewer London forces. The branches also get in the way and prevent the branched molecules from getting as close together as straight chain molecules, also decreasing intermolecular forces.

Answer 7

Alkane + oxygen -> carbon dioxide + water

Answer 8

Carbon monoxide - toxic

Answer 9

Ultraviolet radiation in sunlight provides the initial energy for the reaction to take place.

Answer 10

A reaction mechanism showing the movement of electrons in 3 stages.

Answer 11

Initiation Propagation Termination

Answer 12

- Initiation: the reaction starts when the covalent bond in a halogen molecule is broken by homolytic fission. This forms two reactive halogen radicals. - Propagation: the reaction propagates through a two step propagation chain reaction. In the first step, a halogen radical reacts with a C-H bond forming an ester radical and a molecule of hydrogen + the halogen. In the second step, each ester radical radical reacts with another halogen molecule, forming the organic product and another halogen radical. The two steps continue to cycle in a chain reaction. - Termination: two radicals (one of each kind) collide, forming a molecule with all electrons paired. The are various possibilities. When two radicals collide and react, both radicals are removed, stopping the reaction.

Answer 13

The reaction starts when the covalent bond in a halogen molecule is broken by homolytic fission. This forms two reactive halogen radicals.

Answer 14

The reaction propagates through a two step propagation chain reaction. In the first step, a halogen radical reacts with a C-H bond forming an ester radical and a molecule of hydrogen + the halogen. In the second step, each ester radical radical reacts with another halogen molecule, forming the organic product and another halogen radical. The two steps continue to cycle in a chain reaction.

Answer 15

``` Two radicals (one of each kind) collide, forming a molecule with all electrons paired. The are various possibilities. When two radicals collide and react, both radicals are removed, stopping the reaction. ```

Answer 16

The C-C and C-H sigma bonds are strong C-C bonds are non-polar The electro negativity of carbon and hydrogen is so similar that the C-H bond can be considered to be non-polar

Answer 17

C2H6 + 3.5 H2O -> 2CO2 + 3H2O

C11 & 12 - Organic Chemistry and Alkanes Flashcards

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