Flashcards in Unit 2 Deck (60)
What happens to alkanes or alkenes as their carbon chain length increases?
Their boiling and melting points increase.
They become more viscous (thicker).
They become less flammable.
List three addition reactions that alkenes can undergo.
1. Addition of hydrogen to make alkanes = hydrgenation.
2. addition of halogens to make dihaloalkanes
2. addition of water to make alkanols = hydration
What are saturated straight chain alcohols called and what is their general formula?
general formula CnH2n+1OH
What are alchohols used for?
Used as fuels - burn with clean flame or solvents
What is the name o the alcohol/alkanol with two carbon atoms?
Do alcohols dissolve in water?
Methanol, ethanol and propanol do but solubility deceases with increasing carbon chain length.
Why do alcohols decrease in solubility as the length of the carbon chain increases?
The hydrophobic hydrocarbon chain has increasing length and increasing overall effect.
What is vinegar?
it is a solution of ethanoic acid
What are carboxylic acids?
Give their general formula.
Substances with the carboxyl functional group (-COOH)
general formula is CnH2n+1COOH
What are carboxylic acids used for?
Perservatives (eg pickling in vinegar)
Do carboxylic acids dissolve in water?
methanoic acid, ethanoic acid, propanoic acid and butanoic acid do dissolve in water. BIgger molecules become increasingly insoluble.
What is the carboxylic/alkanoic acid with 4 carbon atoms called?
What pH do carboxylic acids have?
less than 7
List 4 substances that will react with carboxylic acids to make salts.
What salt is made when each of the following reacts with sodium hydroxide?
1) methanol acid
2) ethanoic acid
3) propanoic acid
1) sodium methanoate
2) sodium ethanoate
3) sodium propanoate
Which hydrocarbons are soluble in water?
None of them.
What is the name given to a reaction that takes in heat energy?
What is combustion?
When a substance burns and it combines with oxygen releasing heat energy.
What products are made when a hydrogen burns with lot of oxygen?
carbon dioxide and water
How do you measure how much energy a fuel can give out?
Burn a known mass of it and measure the temperature increase of a fixed volume of water.
Then use E=mcΔT to calculate the energy given out.
E = mcΔT
in the formula above what do each of the letters/symbols stand for?
E = energy given out
m = mass of water heated
c = specific heat capacity of water
ΔT = change in temperature
Why are alcohols good fuels?
They are highly flammable and burn with very clean flames.
What is incomplete combustion?
When there s not enough oxygen so carbon (soot) and carbon monoxide are made instead of carbon dioxide.
What is a hydroxyl group and which homologous series has them?
found in alkanols/alcohols
What is a carboxyl group and which homologous has them?
found in alkanoic acids/carboxylic acids
What would you call an alkanol with three carbon atoms?
propan-1-ol or propan-2-ol depending on were the -OH group is.
What type of reaction is the decolouristation of bromine water
When bromine reacts with an alkene where do bromine atoms go?
One to each side of where the double bond was.
How can you make an alcohol?
React an alkene with water.