Chapter 16 (16.3-16.8) Nomenclature Flashcards by Neel Saraf

what are the three types of hydrocarbons

alkanes, alkenes, alkynes

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characteristics of a homologous series

same functional group
same general formula
same chemical properties
Consecutive members differ by CH2

boiling and melting points increases down a homologous series
common methods of preparation
Viscosity increases
Flammability decreases

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What is a functional group (definition)

An atom or group of atoms in a molecule that dictates how the compound will react

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which hydrocarbon is unsaturated

alkene, alkyne

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Are alkenes or Alkanes more reactive
why

Alkenes - double bond easier to break

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what is the general formula of alkanes

CnH2n+2

eg:- carbon = 7
then hydrogen = 2(7)+2 therefore 16
C7H16

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functional group of alkane

single bond between carbons

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properties of alkanes

insoluble in water
The boiling point of alkanes increases with increasing molecular weight.
The melting point of alkanes increases with an increase in molecular weight.

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naming alkanes

1) select longest chain (straight, L shaped)
2) number closest to the branch
3) all other groups not part of the longest chain should be taken as a branch
4) if there is more than one group present as a branch then written as di,tri etc. and branches are named in alphabetical order eg ethyl, methyl. ethyl comes first

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what is methane

ch4

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what is ethane

c2h6

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what is propane

c3h8

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what is butane

c4h10

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combustion reaction of alkanes

Alkane + oxygen –> co2 + h2o
eg: CH4 + 2o2 –> CO2 + 2H2O

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What is a substitution reaction
Example

One atom or a group of atoms is replaced by another atom or group of atoms

Eg: Photochemical Reaction

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photochemical reaction of alkane

occurs only under presence of light

Alkane + Halogen —–light—–> Alkyl-Halide + Acid
CH4 + Cl2 —–light—–> CH3Cl + HCl

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What does the light do in a photochemical reaction

provides the activation energy required for the reaction

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What happens as the amount of chlorine increases in photochemical reaction

More and more hydrogen atoms are substituted by chlorine atoms

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properties of alkynes

have one less hydrogen than their alkane (methane ch4 /methyl ch3)

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general formula of alkenes

CnH2n

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what is the functional group of alkenes

double bond between the carbon

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naming alkenes

1) select longest chain
2) naming starts closest to the double bond

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properties of alkenes

Unsaturated (reactive) due to double bond between the 2 carbons
known as olefins as when they react with halogens they produce oil.
colorless
odourless
insoluble in water
The boiling points of the compounds increase as the number of carbon atoms in the compound increases.

What is cracking

Process of breaking molecules into smaller ones

What is Zeolite

Hot catalyst used in cracking

cracking of alkanes and alkenes

1) long chain alkane ---heat,pressure,catalyst----> alkene + hydrogen 2) long chain alkane ---heat,pressure,catalyst----> short chain alkane + alkene no.1 eg: c5h12 (pentane) -h,p,c---> c5h10 + h2 no.2 eg: c5h12 (pentane) -h,p,c---> c2h6 + c3h6

Why is cracking performed

Make the best use of petroleum to meet demand Gives alkenes, which aren't found in petroleum

combustion reaction of alkenes

Alkene + oxygen ----> carbon dioxide + water

What is an addition reaction

Turns unsaturated alkenes into a saturated compound. ONLY YILEDS ONE PRODUCT

2 types of addition reactions

hydrogenation of alkene Alkenes + Hydrogen --> Alkanes Hydration of alkenes Alkenes + H2O --h, p, acid c--> Alcohols

hydrogenation of alkene (Conversation from alkene to alkane)

c2h4 + h2 --h,p,c---> c2h6

hydration of alkene

c2h4 (ethene) + H2O <----300c, 60-70 pressure, phosphoric acid-----> C2H5OH

test for unsaturation

bromine water + alkane ---> no colour change (remains orange) indicating that it is saturated bromine water + alkene ----> orange-brown to colorless indicating that it is unsaturated as bromine can be added

what are isomers

compounds that have the same molecular formula but different structural formula

Alkene isomers

1) branch where in the branching in the structure is different 2) unbranch where its the longest chain but placement of the double bond is different

general formula and functional group of alcohol are they a hydocarbon

functional group: OH general formula: CnH2n+1OH Not a hydrocarbon

2 methods to yield alcohol

1) biological method. anaerobic respiration of yeast yields alcohol C6H12O6 -----> 2C2H5OH + 2CO2 2) chemical method, hydration of ethene. C2H4 + H2O (gas) <----300c, 60-70Pa-----> C2H5OH

combustion of Alcohol

C2H5OH + O2 ----> CO2 +H2O highly exothermic reaction, hence alcohol is used as a fuel

oxidation of alcohol

C2H5OH + [O] ----> CH3COOH alcohol on oxidation form carboxylic acid

what is Carboxylic Acid's functional group and general formula Are they a hydrocarbon?

an acid that is made of carbon, hydrogen and oxygen functional group: COOH general formula: CnH2n+1COOH Not a hydrocarbon

formation of carboxylic acid

Biological method: fermentation, while making alcohol expose it to the air for it to form carboxylic acid, through oxidation, adding bacteria could also form carboxylic acid Using alcohol and oxidizing agent:- use potassium permanganate or potassium dichromate as an oxidizing agent. this agent will bring about oxidation on alcohol potassium permanganate MnO4 ---> Mn2+ potassium dichromate CrO7^2- ----> 2Cr2+

reactions of carboxylic acid

carboxylic acid + metal ---> metal carboxylate + h2 carboxylic acid + metal oxide/hydroxide ---> metal carboxylate + H2O CH3COO- always gains electrons

esterification

carboxylic acid + alcohol ----> ester + h2o eg ethanoic acid + methanol ----> methyl-ethanoate + h2o

how to name esters

alcohol + yl, carboxylic acid + ate

How are aklanes, alkenes, alcohol and carboxylic acids linked?

Alkanes - obtained from petroleum/occur naturally Alkenes - cracking Alkanes Alcohols - Alkenes reaction with water Carboxylic acids - Oxidising Alcohols

what is butanol oxidised by

Butan-1-ol is oxidised by acidified potassium manganate

which naturally occurring compounds contain the ester linkage

fats / vegetable oils

what is meant by the term fermentation

sugar (glucose) changed to alcohol (ethanol) c6h12o6 + 2c2h5oh + 2co2 catalysed by enzymes

What type of compound are vegetable oil and biodiesel?

esters

What other useful product is made from vegetable oil by heating it with aqueous sodium hydroxide?

soap

why is biodiesel better for the environment than petroleum-based diesel

both produce carbon dioxide and emit it into the environment but growing plants is needed to make bio fuels and plants remove carbon dioxide from the air

when writing an esters structural formula which compounds structual formula comes first

carboxylic acid-coo-alcohol eg propyl ethanoate ch3-coo-c3h7

How could you show that butanol made from petroleum and biobutanol are the same chemical?

see if they boil at the same temp

2 conditions needed for the fermentation of glucose

Yeast Anaerobic respiration - no oxygen

Why does the concentration of ethanol produced by fermentation not exceed 15% is this an adv or disadv

Disadv - If concentration exceeded 15% it would kill the yeast and hence never exceeds that.

Another disadvantage of fermentation

slow rate of reaction