Module 4 Section 1

Question 1

What is the empirical formula?

Answer 1

The simplest whole number ratio of atoms of each element in a compound

Question 2

What is the molecular formula?

Answer 2

Actual number of atoms of each element in a compound

Question 3

What is the structural formula?

Answer 3

Shows the arrangement of atoms carbon by carbon with the attached hydrogen and functional groups

Question 4

What is a skeletal formula?

Answer 4

Shows the bonds of the skeleton only, with any functional groups

Question 5

What is the displayed formula?

Answer 5

Shows how all the atoms are arranged and the bonds between them

Question 6

What is a homologous series?

Answer 6

Bunch of organic compounds that have the same functional group and general formula

Question 7

What is the general formula for alkanes?

Answer 7

CnH2n+2

Question 8

What is a structural isomer?

Answer 8

Same molecular formula but the structure is different

Question 9

What are the three different types of structural formulas?

Answer 9

Chain isomers - carbon skeleton arranged differently - different physical properties
Positional isomers - functional group on different carbon atom - different chemical and physical properties
Functional group isomers - atoms arranged into different functional groups

Question 10

Alkanes are ……

Answer 10

Saturated - all carbon bonds are single

Question 11

What forces does an alkane have?

Answer 11

Covalent bonds in the molecules and induced dipole-dipole interactions holding them all together

Question 12

What affects the boiling point of an alkane?

Answer 12

Longer= stronger - more surface area

Branches chain = lower boiling point - pack closely have smaller molecular surface area

Question 13

What is produced when alkanes are burnt completely on oxygen?

Answer 13

Carbon dioxide and water

Question 14

Why do alkanes make good fuels?

Answer 14

Release so much energy when the burn

Question 15

All gases at the same temperature and pressure have the same ……………

Answer 15

Molar Volume

Question 16

What happens when alkanes are burnt in limited oxygen?

Answer 16

Carbon monoxide and water is produced

Question 17

Why is the production of carbon monoxide a problem?

Answer 17

Poisonous - binds to the haemoglobin in the blood - less oxygen can be carried around the body

Question 18

What is Heterolytic fission?

Answer 18

The bond breaks unevenly with one of the bonded atoms receiving both electrons - firms a positively charged cation and a negatively charged anion

Question 19

What is homolytic fission?

Answer 19

The bond breaks evenly- each bonding atom receives one electron from the bonded pair - two electrically uncharged radicals are formed - very reactive

Question 20

How are haloalkanes formed?

Answer 20

Halogens and alkanes react in photochemical reactions- started by by light - requires ultraviolet light
A hydrogen is substituted by chlorine or bromine - free-radical substitution reaction

Question 21

Describe the reaction mechanism of chlorine and methane?

Answer 21

Institution - free radicals are produced
Sunlight provides energy to split cl2 - splits equally by homolytic fission creative a highly reactive unpaired election - few eradicate

Question 22

What is a general formula?

Answer 22

Algebraic formula that can describe any member of a family of compounds

Question 23

For free radical substitution what is the reaction mechanism

Answer 23

Initiation - radicals produced - bond breaks evenly in homolytic fission
Propagation - free radicals are used up and created in a chain reaction
Termination - free radicals are mopped up - stable molecule is formed when two free radicals join together

Question 24

What are the problems with free radical reactions?

Answer 24

Mixtures are produced which need to be separated - by using excess methane there is a greater chance that cl radical will collide with methane
A mixture of positional isomers can form

Question 25

What is the general formula for an alkane?

Answer 25

CnH2n