Organic Families 1 Flashcards
What is homologous series
A homologous series is a family of organic compounds with the same general formula, same chemical properties with successive members differing by CH2
Name the eight homogous series studies in LC
alkanes , alkenes, alkynes,
alcohols, aldehydes ,ketones, carboxylic acids, esters
What is Hydrocarbon
A hydrocarbon is a compound that contains carbon and hydrogen ONLY
IUPAC root for 1 Carbon
Meth
IUPAC root for 2 Carbon
Eth
IUPAC root for 3 Carbon
Prop
IUPAC root for 4 Carbon
But
IUPAC root for 5 Carbon
Pent
IUPAC root for 6 Carbon
Hex
IUPAC root for 7 Carbon
Hept
IUPAC root for 8 Carbon
Oct
What is the general formula for Alkanes
Cn H2n+2
What is the ending for Alkanes
Ane
What is a saturated compound
Has only single bonds between the carbon atoms in the compound ( no double or triple bonds)
What are structural isomers?
Compounds that have the same molecular formula but different structural formulae
How many structural isomers are there for the forth members of the alkane family?
2
How many structural isomers are there for the fifth members of the alkane family?
3
How many strain how only sigma bonding takes place between carbon atoms in alkane molecules
Alkanes are saturated compounds ( contain only single bonds) between the carbon atoms
Single bonds are always formed by a sigma bond
Give two applications of the alkanes
1 alkanes are excellent fuels ( for cooking and heating)
2 Alkanes can be used as lubricating oil in machinery
What are Chloroalkanes
Coumpounds in which one or more of the hydrogen atoms in an alkane molecule have been replaced by chlorine atoms
Give two applications of the chloroalkanes
Solvents - used in dry cleaning
Paint stripper
What’s the general formulas for alkenes
CnH2n
What do alkenes end with
Ene
Are alkenes saturated or unsaturated compounds
Unsaturated - compounds containing one double bond between some of the carbon atoms in the molecules
What is an unsaturated compound?
Unsaturated compounds has double or triple bonds between some of the carbon atoms in the molecule
What is the molecular formula and the IUPAC name for the 1st member of the alkenes
C2H4
Ethene
You have to number the carbon chain in such a way that the ….
Double bond is coming from the lowest carbon possible and name the main chain based on its number of carbons
How many isomers of the third member of the alkene series
3
Explain how sigma and pi bonding take place between carbon atoms in alkene molecules
Alkenes are unsaturated compounds, contain a double bond between two of the carbon atoms.
Double bonds are formed by a sigma bond and a pi bond
name the physical properties of ethyne
ethene is a colourless gas with a sweet smell
it is insoluble in water but dissolved in non-polar substances eg cytohexane
Account for the greater reactivity of alkenes compared to alkanes
Alkenes are unsaturated.
This double bond has a high electron density and includes a pi bond which is weaker and easily broken
You have to number the carbon chain in such a way that the ….
Double bond is coming from the lowest carbon possible and name the main chain based on its number of carbons
Give two industrial applications of alkenes
1 ethene is used to speed up the ripening of fruit
2 polyethene is used inplastic production
Give the word equation for the experiment of preparing ethene
Ethanol —-(aluminium oxide—-> ethene + water
Give the chemical equation for preparing ethene
C2H5OH —(Al2O3) —> C2H4 + H2O
Describe the procedure to prepare ethene
Glass wool soaked in ethanol
Aluminium oxide gently heated allowing the ethanol to vaporise and pass over the Aluminium Oxide (dehydrating agent).
Ethanol is dehydrated to ethene + water
Ethene is carried by delivery tube and collected over a basin of water using a beehive shelf.
Describe the physical properties of ethene
ethene is a colourless gas with a sweet smell
its insoluble in water but dissolves in non-polar solvents eg- Cyclohexane
(like dissolves like)
What is combustion?
burning in oxygen
describe the procedure for the combustion of ethene
place a lighted splint into a test tube of ethene gas. add lime water to the test tube, stopper and shake
what is the postive result of the combustion of ethene
ethene burns with a bright yellow flame
limewater turns milkey white proving CO2 was formed in the combustion
write a balanced chemical equation for the complete combustion of ethene
C2H4 + 3O2 -> 2CO2 + 2H2O
write a balanced chemical equation to explain why CO2 turns limewater white
CO2 + Ca (OH)2 -> CaCO3 downwards arrow
carbon dioxide + limewater(calcium hydroxide) -> calcium carbonate
Describe the test to see if ethene is unsaturated using bromine water
add red bromine water to a test tube of ethene gas, stopper and shake
result:redbromine water turns colourless - ethene is unsaturated
(is anything was saturated it would remain red)
what type of reaction occours when bromine is added to ethene gas
addition reaction- the adding of a bromine molecules across a doublr bond, breaking the double bond
write a balanced equation for the test for unsaturation using bromine water
ethene + bromine -> 1,2 dibromoethane
C2H4 + Br2 -> C2H4Br2
explain how to test for unsaturation using acdified potassium manganate VII
and give the postive result
add purple KMnO4 / acidified potassium managante VII, stopper and shake.
purple acdified potassiu manganate (VII) turns colourless
ethene is unsaturated
what type of reaction is the preparation of ethene known as
elimation / dehydration reaction
what is the function of the aluminium oxide in the testing of the properties of ethene
aluminium oxide acts as a dehydrating agent
is a catalyst for the reaction
what is the apperance of aluminium oxide
white powder
why is the aluminium oxide heated gently/ why is the ethnol not heated directly
to avoid the ethnol vapourising too quickly and passing over the aluminium oxide too quickly - little ethanol would be converted into ethene
what is the function of the glass wool in this expeirment
to soak up the ethanol and keeps it at one end of the test tube- stops ethanol from being directly heated
state and explain three saftey precautions in this expeirment for ethene
- ensure the test tuble stopper on the testube is airtight
ethene and ethanol are flammable- essential to keep the, away from the busen burner flame to prevent a fite
2.Wear gloves and use thongs
glass wool is irritant to skin- avoid touching
3.raise the apparatus from the water before turning the busen burner off
avoid suck back of water up delivery tuble-cold water being sucked back in the hot test tuble could cause it to shatter
why are the first few test tubles of gas collects discarded
the first few test tubles consist mostly of displaced air and ethanol gas
What is the ending for alkynes
yne
are alkynes saturated or unsaturated compounds
alkynes are unsaturated compounds containing one triple bond between two of the carbons
give an application of ethyne
ethyne gas used in welding and cutting metals
describe the procedure to prepare ethyne
calcium carbide is placed in a reaction flask using a spatula, the dropping funnel is set above filled with water. The water is slowly added from the droppinf funel. Fizzing will occour in the reaction flask as ethyne is produced. The ethyne gas produced is passed through acidified copper sulfate to remove impurities
the pure ethyne gas is collected over water
write a balanced equation to prepare ethyne
CaC2 +2H2O -> Ca(oh)2 + C2H2
calcium carbide + water -> calcium hydroxide + C2H2
Describe the physical properties of ethyne
ethyne is a colourless gas with a sweet smell
its insoluble in water but dissolved in non-polar substanced eg cytohexane
decribe the combustion of ethyne and name its postive result for its test
ethyne burns with a very bright, very smoky yellow flame, with a lot of soot formed as a result of unburned carbon
limewater turns milky white proving carbon dioxide was formed in the combustion
compare the flame observed when observing ethyne and ethene
the flame observed when burning ethyne is brighter and smokier than when burning ethene
how does the flame used in oxyacetylene welding, where ethyne is burned in air in a combustion test
ethyne will burn in pure oxygen with a hotter, cleaner flame with less smoke/soot
Write a balanced equation for the complete combustion of ethyne
C2H2 +2 1/2 O2 -> 2CO2 +H2O
What do ALL organic compounds produce when combusted completely
Carbon dioxide and water vapour
Describe the test for unsaturation in ethyne using bromine water and its result
Procedure- add red bromine water to a test tube of ethyne gas stopper and shake, result, red bromine water turns colourless - ethyne is unsaturated
Testing for unsaturation using acidified potassium manganate VII on ethyne and its result
Add to a tube of ethyne, stopper and shake purple potassium manganate VII turns colourless- ethyne is unsaturated
Outline 2 safety precautions in production of ethyne
Ethyne is explosive with air- keep any naked flame away from the apparatus
Use spatula to place calcium dicarbide into flask- its and irritant to skin
Give three observations in the reaction flask as the reaction proceeds
Fizzing is observed
A white substance formed
The reaction flask gets hot
Describe the appearance of calcium carbide
Calcium carbide is a grey- black solid
Explain why fizzing occurs in the reaction flask
Ethyne gas is produced
Explain the white substance that formed in the flask as the reaction proceeds
The white substance formed as a result of the production of calcium hydroxide Ca(OH)2
Explain why the flask gets warm as the reaction proceeds
The reaction between calcium carbide and water is exothermic ( gives out heat)
Why must the products of the reaction be passed through acidified copper sulfate
The ethyne formed is not pure, passing it through acidified copper sulfate removes impurities
Name three impurities that could be present in the ethyne gas produced that are removed by the acidified copper sulfate
Hydrogen sulfide
Phosphine
Ammonia
Why are the first few test tubes of gas collected and discarded
they contain mostly of displaced air and not ethyne gas
