TOPIC 9 - Separate Chemistry 2 Flashcards
Colour of lithium ion flame
Red
Colour of sodium ion flame
Yellow
Potassium ion flame color
Lilac
Calcium ion flame
Orange-red
Copper ion flame color
Blue-green
Test for metal ions involving precipitate
Add sodium hydroxide solution to the solution and metal hydroxide may precipitate out of solution.
Aluminium precipitate color and ionic equation
White before redissolving in excess sodium hydroxide w colourless solution.
Al3+ + 3OH-»_space; Al(OH)3
Calcium precipitate color and ionic equation
White
Ca2+ + 2OH-»_space; Ca(OH)2
Copper precipitate color and ionic equation
Blue
Cu2+ + 2OH-»_space; Ca(OH)2
Iron(II) precipitate color and ionic equation
Green
Fe2+ + 2OH-»_space; Fe(OH)2
Iron(II) precipitate color and ionic equation
Brown
Fe3+ + 3OH-»_space; Fe(OH)3
How do you work out whether a substance contains ammonium ions?
Add sodium hydroxide solution and gently heat, ammonia gas will be given off.
How do you test for ammonia gas?
Hold a piece of damp red litmus paper over and ammonia gas will turn it blue.
How do you test for halide ions?
Add dilute nitric acid before a few drops of silver nitrate solution.
Chloride precipitate
When testing for anions
White precipitate of silver chloride
Bromide precipitate
When testing for anions
Cream precipitate of silver bromide
Iodide precipitate
When testing for anions
Yellow precipitate of silver iodide
How do you test for carbonate ions?
Symbol equation?
Add dilute acid and mixture will fizz as it will produce carbon dioxide gas.
CO32- + 2H+»_space; CO2 + H2O
How do you test for sulphate ions?
Add dilute hydrochloric acid before adding barium chloride solution, sulfate ions will produce a white precipitate of barium sulfate.
Flame photometry
Instrumental method allowing identification of ions in a dilute solution. Each ion produced a unique line spectrum.
Why is flame photometry better than flame tests on specific occasions?
As can identify ions within a mixture which flame tests can’t.
Advantages of using machines to analyse unknown substances
V sensitive
V fast
V accurate
Homologous series
A group of chemicals w similar chemical structures and functional group while sharing a trend in chemical properties.
Alkanes
Homologous series of hydrocarbons w general formula CnH2n+2. They are saturated.
Functional group
A group of atoms that determine how a molecule reacts.
Alkenes
Homologous series of hydrocarbons w a C=C functional group, unsaturated .
CnH2n
How do you test for an alkene?
What reaction does it involve? Why?
Place in Bromine water, alkene will decolourise (orange to transparent).
Addition reaction occurs as bromine is added across the alkene double bond.
Complete combustion of hydrocarbons
Hydrocarbon+ oxygen» carbon dioxide + water
Polymers
Substances of high average relative molecular mass, composed of monomers.
Monomers in addition polymers
Have double bond
Addition polymerisation
Unsaturated monomer molecules opening up their double bonds to form polymer chains.
How are formulas of polymers written?
(Monomer formula)n
How do you draw the displayed formula of an addition polymer?
Join monomer carbons together w no double bonds w brackets on each side and stick n on end
How do you draw the displayed formula of an addition monomer?
Draw out unsaturated monomer and stick n before it
Condensation polymerisation
2 different monomers (w 2 functional groups) reacting together to create long chains of alternating monomers. For each new bond formed, a small molecule (like water) is lost.
Polyesters
Di carboxylic acid monomers reacted with diol monomers.
Ester link
A carboxylic acid group reacting with an alcohol group.
Molecule of water is formed each time an Ester link is made.
Examples of non-synthetic polymers
DNA (nucleotide monomers)
Proteins (amino acid monomers in condensation polymerisation)
Starch / cellulose (sugar monomers)
2 methods of disposing polymers
Landfill
Incineration
Positives and negatives of landfill
:) polymers can be difficult and expensive to separate and recycle.
:( valuable land is used up and most polymers are no biodegradable
Positives and negatives of incineration
:) produces much energy to generate electricity.
:( produces toxic gases and CO2, contributing to global warming
Advantages of recycling
Reduces amount of a non-biodegradable waste filling up landfill sites.
Reduces emissions.
Uses less water and energy resources than when making new plastics.
Reduces amount of crude oil needed to produce more plastics.
Saves money and creates jobs
Disadvantages of recycling
Separation of polymers can be difficult/expensive.
Quality of polymer product is reduced when mixed.
Finite number of times through which a polymer can be recycled.
Melting down polymers can release dangerous gases
Alcohols
Have an -OH functional group w the same general formula (CnH2n+1)
What is formed by the oxidation of alcohols?
Carboxylic acids
Carboxylic acids
Have a -COOH functional group w the general formula Cn-1H2n-1COOH.
Fermentation
The process of using yeast to convert a type of carbohydrate (sugars) into alcohol.
Equation for fermentation
C6H12O6 >yeast> 2C2H5OH + 2CO2
Glucose> ethanol + carbon dioxide
How do you make a solution of ethanol via fermentation?
Mix yeast and carbohydrate solution in sealed, clean container in warmth (between 30/40°C). Needs to be kept in anaerobic conditions
When concentrated of alcohol reaches 10-20%, fermentation will stop as yeast is killed by alcohol, falling to bottom of container.
How do you produce a more concentrated alcohol?
Fractional Distillation
Why does fractional distillation work on the solution of alcohol?
Ethanol has a lower boiling point than water so evaporates up fractionating column while water stays as liquid.
What equipment is used to condense the ethanol vapour
A Liebig condenser.
How do you measure the efficiency of alcohol as a fuel?
Put alcohol in spirit burner and measure mass of burner w fuel (using mass balance).
Measure 100 cm cubed of distilled water into copper calorimeter and insulate w draught excluder, covering w insulating lid after putting thermometer inside.
Take initial temp of water and light wick.
Stir throughout w a thermometer and blow out burner when water temp has risen by 20°C.
Reweigh burner and fuel.
Repeat w other alcohols
Variables to keep same when burning alchol
Volume of water
Height of container above wick.
Length of wick.
Moles of alcohol.
How does chain length of alcohol affect efficiency
Longer chain length = more efficient fuel.
Size of nanoparticles
How many atoms do they contain?
1-100 nanometers
Roughly few hundred atoms.
Surface area to volume ratio of nanoparticles
As particles decrease in size, surface area to volume ratio increases.
Therefore can act as catalyst as much more of atom is available to interact w substances they come into contact w.
Uses of nanoparticles
CATALYST (large surface area to volume ratio)
COSMETICS (transparent but work)
NANOMEDICINE (can hold medicine and transport into body)
LUBRICANT (artificial joints and gears)
CONDUCTORS (electric circuits)
SPORTS EQUIPMENT (strengthens plastics)
Surgical masks (silver nanoparticles have antibacterial properties)
Risks of nanoparticles
health implicationsUnaware of long-term
Could build up in cells
Uses of polymers
Water pipes
Plastic bags and squeeze bottles
Thermal insulators
Plastic kettles
Properties of polymers
Strong, rigid, light, stretchy Heat-resistant Insulator Cheaper Less dense Degrade and break down over time
Clay uses
Building material (bricks)
Clay properties
Easily mouldable
Strong
Glass properties
Transparent strong brittle
Easily mouldable
Composites
Reinforcement embedded in matrix
Properties depend on materials mixed.
Expensive
Metals properties and uses
Conductor of heat and electricity High density Malleable Can form alloys Corrosion resistant
Examples of ceramics
Properties
Clay
Glass
Brittle, stiff, strong, hard-wearing, don’t degrade or corrode
