C10.1 - C10.4 - Organic Reactions✔️ Flashcards
What are organic compounds?
The substance that form the basis of all living things,organic molecules all contain carbon atoms
What is a homologous series?
A “family” of organic compounds with the same functional group
What is the genreal formula of the alkenes containing one double carbon bond?
CₙH₂ₙ
Why do Alkenes burn with a smokier yellow flame compared with Alkanes?
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
Why are Alkanes used as fuel instead of Alkenes?
Alkanes release more energy per mole in combustion than Alkenes - during complete combustion you get:
Ethene + oxygen - carbon dioxide + water
Why are Alkenes more reactive then Alkanes?
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
Why are Alkenes unsaturated compounds?
Because of the double carbon bonds (C=C) their molecules do not contain the maxium number of hydrogen atoms possible in a hydrocarbon molecule
How is a saturated hydrocarbon formed?
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
What is an Alkene?
Unsaturated Hydrocarbons which only contain hydrogen and carbon and have at least 1 double carbon bond which allows it to undergo addition reactions
What is an Alkane?
A saturated hydrocarbon that does not have a double bond
3 types of addition reactions with Alkenes?
-hydrogen
-water(steam)
-halogens
Reaction between alkene and water?
Alkene + water (steam) → alcohol.
Reaction between alkene and hydrogen - hydrogenation?
Alkene + hydrogen → saturated alkane
Why does the addition reaction of an alkene with water produce ethanol?
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
How do we seperate the ethanol(alcohol) produced with the reaction between an Alkene and water from any unreacted ethene (hydrocarbon) and water?
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
Difference between an alkenes reaction with hydrogen and halogen
Reaction between a alkene and halogen doesn require any catalyst
What is the test used to distinquish between alkenes and alkanes?
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)
Explain why we can use the reaction of ethene and bromine to distinguish alkenes from alkanes?
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
What is an alcohol?
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
What is the formula for ethanol?
C₂H₅OH
What are Carboxylic acids?
Carboxylic acids have a functional group made up of a C=O bond and C-OH bond on the same carbon shortend to COOH
What are Esters?
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
How can ethanol be made?
-Reacting the alkene ethene with water in the presence of a catalyst
-fermenting sugars from plant material with yeast
Uses of alcohols?
Used as solvents and fuels with ethanol being one of the main alchohols used in alcoholic drinks
Reaction for making ethanol through fermentation?
Glucose → (yeast) → ethanol + carbon dioxide
C6H12O6 (aq) → 2C2H5OH(aq) + 2CO2(g)
What property makes alcohols usefull as solvents?
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
What are methylated spirits?
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
Reaction for the combustion of alcohols?
Ethanol + oxygen - carbon dioxdie + waterC
C2H5OH + 3 O2 → 2 CO2 + 3 H2O
Uses of ethanol?
Used as biofuel in cars and in spirit burners - it burns with a ‘clean’ blue flame in the reaction ethanol + oxygen - carbon dioxide + water
Alcohols reaction with sodium?
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
Oxidation with acids?
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
Carboxylic acids reaction with metal carbonate?
Forms a salt,water and carbon dioxide
Ethanoic acid + sodium carbonate - sodium ethanoate + water + carbon dioxide
Why are carboxylic acids called weak acids?
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
Why do carboxylic acids react slower then strong acids?
Carboxylic acids have a high pH meaning a lower concentration or H+ ions which results in a slower reaction compared with strong acids
Carboxylic acids reaction with alcohols?
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
Equation for making esters with carboxylic acids?
Carboxylic acid + ethanol - (acid catalyst) - ester + water
Define a strong acid?
all the molecules breaks down to form H+ ions when added to wat
Define a weak acid?
only a small fraction of the molecules break down to form H+ ions when added to water
