C10.1 - C10.4 - Organic Reactions✔️

Question 1

What are organic compounds?

Answer 1

The substance that form the basis of all living things,organic molecules all contain carbon atoms

Question 2

What is a homologous series?

Answer 2

A “family” of organic compounds with the same functional group

Question 3

What is the genreal formula of the alkenes containing one double carbon bond?

Answer 3

CₙH₂ₙ

Question 4

Why do Alkenes burn with a smokier yellow flame compared with Alkanes?

Answer 4

Because there is incomplete combustion.for the same reason,they also release less energy per mole in combustion than Alkanes so Alkanes are used as fuel where as Alkenes are not

Question 5

Why are Alkanes used as fuel instead of Alkenes?

Answer 5

Alkanes release more energy per mole in combustion than Alkenes - during complete combustion you get:
Ethene + oxygen - carbon dioxide + water

Question 6

Why are Alkenes more reactive then Alkanes?

Answer 6

It is the double carbon bonds that makes the Alkenes far more reactive the Alkanes - molecules that react with Alkene molecules ‘add’ to the Alkene across their double bond

Question 7

Why are Alkenes unsaturated compounds?

Answer 7

Because of the double carbon bonds (C=C) their molecules do not contain the maxium number of hydrogen atoms possible in a hydrocarbon molecule

Question 8

How is a saturated hydrocarbon formed?

Answer 8

The addition of a hydrogen molecule (H₂) across the double bond of an unsaturated hydrocaron (Alkene) in a process called hydrogenation which takes place in the presene of a nickel catalyst

Question 9

What is an Alkene?

Answer 9

Unsaturated Hydrocarbons which only contain hydrogen and carbon and have at least 1 double carbon bond which allows it to undergo addition reactions

Question 10

What is an Alkane?

Answer 10

A saturated hydrocarbon that does not have a double bond

Question 11

3 types of addition reactions with Alkenes?

Answer 11

-hydrogen
-water(steam)
-halogens

Question 12

Reaction between alkene and water?

Answer 12

Alkene + water (steam) → alcohol.

Question 13

Reaction between alkene and hydrogen - hydrogenation?

Answer 13

Alkene + hydrogen → saturated alkane

Question 14

Why does the addition reaction of an alkene with water produce ethanol?

Answer 14

The waters (H₂O) splits into a H atom and an O-H group which bond to the carbon atoms creating an alcohol - for example
Ethene + steam - (catalyst) - ethanol

Question 15

How do we seperate the ethanol(alcohol) produced with the reaction between an Alkene and water from any unreacted ethene (hydrocarbon) and water?

Answer 15

If it is ethene it can be seperated by cooling down the mixture which causes the water and ethanol to condense into liquid while ethene stays as gas (due to low boiling point) to seperate water and ethanol we have to use fractional disilation

Question 16

Difference between an alkenes reaction with hydrogen and halogen

Answer 16

Reaction between a alkene and halogen doesn require any catalyst

Question 17

What is the test used to distinquish between alkenes and alkanes?

Answer 17

Use bromine (which has an orange colour) and add to ethene and shake they react to form dibromoethane (because all the bromine is used up the orange colour disapears)

Question 18

Explain why we can use the reaction of ethene and bromine to distinguish alkenes from alkanes?

Answer 18

alkenes have double bonds so they are more reactive and react with the bromine to decolourise it - alkanes are saturated so they have no double bonds for the bromine to be added to so the reaction remains orange

Question 19

What is an alcohol?

Answer 19

Alcohol molecules all contain the hydroxyl (OH group) they are a homologous series and have a general formula ( CₙH₂ₙ + ₁OH )there names also all end in -ol

Question 20

What is the formula for ethanol?

Answer 20

C₂H₅OH

Question 21

What are Carboxylic acids?

Answer 21

Carboxylic acids have a functional group made up of a C=O bond and C-OH bond on the same carbon shortend to COOH

Question 22

What are Esters?

Answer 22

Esters are formed by the condensation reaction between an alcohol and a carboxylic acid. This is known as esterification and always contain the COO functional group

Question 23

How can ethanol be made?

Answer 23

-Reacting the alkene ethene with water in the presence of a catalyst

-fermenting sugars from plant material with yeast

Question 24

Uses of alcohols?

Answer 24

Used as solvents and fuels with ethanol being one of the main alchohols used in alcoholic drinks

Question 25

Reaction for making ethanol through fermentation?

Answer 25

Glucose → (yeast) → ethanol + carbon dioxide

C6H12O6 (aq) → 2C2H5OH(aq) + 2CO2(g)

Question 26

What property makes alcohols usefull as solvents?

Answer 26

Alcohols with smaller molecules mix very well wih water, giving neutral solutions - the alcohol can also dissolve many organic compounds which makes them usefull for solvents for example you can remove ink stains from markers with methylated spirits

Question 27

What are methylated spirits?

Answer 27

Mainly ethanol but has more toxic methanol mixed with it - purple die and other substances are also added to make it unpleasant to drink to try and discourage alcoholics drinking them

Question 28

Reaction for the combustion of alcohols?

Answer 28

Ethanol + oxygen - carbon dioxdie + waterC
C2H5OH + 3 O2 → 2 CO2 + 3 H2O

Question 29

Uses of ethanol?

Answer 29

Used as biofuel in cars and in spirit burners - it burns with a ‘clean’ blue flame in the reaction ethanol + oxygen - carbon dioxide + water

Question 30

Alcohols reaction with sodium?

Answer 30

Alcohols react similary with sodium metal as they do with water - for example with ethanol the sodium effervesces (gives off bubbles of gas), producing hydrogen gas and it also gets smaller and smaller as it forms a solution of sodium ethoxide in the ethanol

Sodium + ethanol - sodium ethoxide + hydrogen

Question 31

Oxidation with acids?

Answer 31

Combustion is one way to oxidise an alcohol however when you use chemical agents you get different products - the same reaction takes place if ethanol is left exposed to air becauase microbes in the air produce ethanoic acid seen if you leave a bottle of wine open for a wile it will smell like vinegar

Ethanol + oxygen atoms gained from oxidising agent - ethanoic acid + water

Question 32

Carboxylic acids reaction with metal carbonate?

Answer 32

Forms a salt,water and carbon dioxide

Ethanoic acid + sodium carbonate - sodium ethanoate + water + carbon dioxide

Question 33

Why are carboxylic acids called weak acids?

Answer 33

Strong acids completely ionise in water whereas weak acids only partialy ionise - with carboxylic acids,most of the molecules stay as they are and only a small proportion will ionise in their solutions so they have a higher pH(meaning a lower concentration of H+ ions) than stronger acids resulting in a slower reaction with a metal carbonate

Question 34

Why do carboxylic acids react slower then strong acids?

Answer 34

Carboxylic acids have a high pH meaning a lower concentration or H+ ions which results in a slower reaction compared with strong acids

Question 35

Carboxylic acids reaction with alcohols?

Answer 35

React to make esters (ester formend have distinctive smells and are volatile meaning they evaporate easily and are used in perfumes and food flavoruing) water is formend in this reversible reaction for example:

Ethanoic acid + ethanol - (sulfuric acid catalyst) - ethyl ethanoate + water

Question 36

Equation for making esters with carboxylic acids?

Answer 36

Carboxylic acid + ethanol - (acid catalyst) - ester + water

Question 37

Define a strong acid?

Answer 37

all the molecules breaks down to form H+ ions when added to wat

Question 38

Define a weak acid?

Answer 38

only a small fraction of the molecules break down to form H+ ions when added to water