C10 - Organic reactions Flashcards
what is the general formula for alkenes?
CnH2n
Why are alkenes unsaturated?
They have a double carbon-carbon bond (C=C), meaning they have two fewer hydrogen atoms than alkanes with the same number of carbons. (Not all carbon electrons are involved in bonding.)
Name the first four alkenes.
Ethene, propene, butene, pentene.
Why do alkenes burn with smoky flames?
Due to incomplete combustion in air.
What type of reactions do alkenes undergo with hydrogen, water, and halogens?
Addition reactions across the double bond (C=C becomes C-C).
What is the functional group in alcohols?
–OH (hydroxyl group).
Name the first four alcohols.
Methanol, ethanol, propanol, butanol.
Describe the reaction of alcohols with sodium
They produce hydrogen gas.
What happens when alcohols are added to water?
They form neutral solutions.
How is ethanol produced by fermentation?
By fermenting sugars with yeast in anaerobic conditions at 25-50°C.
What is the functional group in carboxylic acids?
–COOH
Name the first four carboxylic acids
Methanoic acid, ethanoic acid, propanoic acid, butanoic acid.
What happens when carboxylic acids react with carbonates?
They produce carbon dioxide, water, and a salt.
Why are carboxylic acids considered weak acids?
They do not fully ionise in water, resulting in a higher pH compared to strong acids.
What is formed when carboxylic acids react with alcohols?
Esters (plus water). this is a condensation reaction (as produces a small molecule as well)
what is formed when ethene reacts with each of hydrogen, steam and bromine.
hydrogen: ethane
steam: ethanol
bromine: Dibromoethane.
What are three reactions of alcohols?
1) Burn in air to produce CO2 and water.
2) Dissolve in water to form a neutral solution (pH 7).
3) React with sodium to produce hydrogen and a salt.
What happens when alcohols are oxidised?
They form carboxylic acids.
What are some uses of alcohols?
Solvents, fuels, alcoholic drinks (ethanol), antifreeze (methanol).
How is ethanol produced by fermentation?
Sugar is converted into ethanol and carbon dioxide using yeast enzymes, at ~35°C in anaerobic conditions. (Equation: glucose → ethanol + carbon dioxide.)
Name the first four carboxylic acids.
Methanoic acid, ethanoic acid, propanoic acid, butanoic acid
how do carboxylic acids behave in water?
They produce acidic solutions (pH less than 7).
What do carboxylic acids produce when they react with metal carbonates?
A salt, water, and carbon dioxide
What do carboxylic acids form when reacting with alcohols in the presence of an acid catalyst?
Esters.
Are carboxylic acids weak or strong acids and why?
They are weak acids as only partially ionise in water, releasing fewer H+ ions.
