Topic 9 Flashcards
Why is the test for ions unique?
Each test is unique- it gives certain results depending on the ions present.
How can you test for a metal ion?
You can test for various metal ions by putting your substance in a flame and seeing what colour the flame goes.
What colour do Lithium ion (Li+) give when put in the flame?
Lithium ions give a red flame
What colour do Sodium ions (Na+) give when put in the flame?
Sodium ions give a yellow flame
What colour do Potassium ions (K+) give when put in the flame?
Potassium ions give a lilac flame
What colour do Calcium ions (Ca2+) give when put in the flame?
Calcium ions give an orange- red flame
What colour do copper ions (Cu2+) give when put in the flame?
Copper ions give a blue- green flame
Are metal hydroxides soluble or insoluble?
Many metal hydroxides are insoluble and precipitate out of solution when formed.
What do some hydroxides have?
Some hydroxides have a characteristic colour
Describe the test for metal hydroxides:
1) Add a few drops of sodium hydroxide to a solution of the mystery compound.
2) If a hydroxide precipitate forms, you can see it colour to tell which metal ion was in the compound
What is colour of precipitate of Aluminium ion?
White at first but then redissolves in excess NaOH to form a colourless solution.
What is colour of precipitate of Calcium ion?
White
What is colour of precipitate of Copper ion?
Blue
What is colour of precipitate of Iron (II)?
Green
What is colour of precipitate of Iron (III)?
Brown
What is the chemical test for ammonia ions?
1) To work out whether a substance contains ammonium ions(NH4+), all you need to do is add some sodium hydroxide solution to a solution of your mystery substance and gently heat it. If ammonia gas is given off, it means that there are ammonium ions in your mystery substance.
What is the chemical test for ammonia gas?
1) You can test for ammonia gas by holding a piece of damp red litmus paper over it. If the mystery gas is ammonia, it will turn blue.
Why is it not a good to smell the ammonia gas?
Ammonia has a distinctive smell and at high concentrations, ammonia is an irritant and toxic.
How can you test for carbonates using dilute acids?
1) To test for carbonates ions in solution add some dilute acid.
2) If there are carbonate ions present, the mixture will fizz- this is because the carbonate will react with the acid to produce carbon dioxide gas.
How can you test for carbon dioxide?
You can check to see if a gas is carbon dioxide by bubbling it through lime water. If it is carbon dioxide, the lime water turns milky.
How can you test for sulfate ions using barium chloride solution?
1) To test for sulfate ions in solution, first add some dilute hydrochloric acid to the test sample- this stops any precipitation reactions not involving sulfate ions from taking place.
2) Then add some barium chloride solution. If there are sulfate ions in the solution, a white precipitate of barium sulfate will form
How can you test for halide ions using silver nitrate solution?
To test for halide ions, add some dilute nitric acid followed by a few drops of silver nitrate solution.
What colour precipitate does chloride give ?
A chloride gives a white precipitate of silver chloride.
What colour precipitate does bromide give ?
A bromide gives a cream precipitate of silver bromide.
What colour precipitate does iodide give ?
An iodide gives a yellow precipitate of silver iodide.
What is flame photometry?
Flame photometry is an instrumental method that allows you to identity ions in a dilute solution.
What does each ion produce in a flame photometry?
Each ion produces a unique line spectrum with different lines present different places.
What does the intensity of the wavelength suggest?
The intensity of the measured wavelength indicates the concentration of that ion in solution.
How can you work out the concentration?
You can work the concentration from intensity using a calibration curve?
What can flame photometry be used for?
Flame photometry can also be used to identify different ions in mixtures.
Why is flame photometry more useful than flame test?
As flame test only work for substances that contain a single metal ion.
What are the advantages of using flame photometry?
1) Very sensitive- they can detect even the tiniest amounts of substances.
2) Very fast and test can be automated.
3) Very accurate- they don’t involve human error, like manual analysis does.
What is a homologous series?
A homologous series is a group of chemicals that have similar chemical structures.
What are alkanes?
Alkanes are a homologous series.
What atoms do alkanes contain?
Alkanes contain just carbon and hydrogen atoms
What is the general formula of alkanes?
CnH2n+2
What do different alkanes have?
Different alkanes have different lengths
What is the formula for methane?
CH4
What is the formula for ethane?
C2H6
What is the formula for propane?
C3H8
What is the formula for butane?
C4H10
Are alkanes saturated or unsaturated?
Alkanes are saturated as all the atoms have formed bonds with as many other atoms as they can.
Alkanes DO NOT have double carbon bonds.
What do members of a homologous series contain?
The same functional group
Are alkenes part of the homologous series?
Yes
What are alkenes?
Alkenes are part of the homologous series with one carbon double bond.
What is the general formula for alkenes?
CNH2N
This means that they have twice as many hydrogen as carbons.
Why are alkenes known as unsaturated?
As they can make more bonds- the double bond can open up, allowing two carbon atoms to bond with other atoms.
What is the formula for ethene?
C2H4
What is the formula for propene?
C3H6
What is the formula for But-1-ene?
C4H8
What is the formula for But-2-ene?
C4H8
What is the difference between But-1-ene and But-2-ene?
In but-1-ene the double bond is at the beginning or the end of the chain, but in but-2-ene the double bond is in the middle.
How can you test for alkene using bromine water?
When shaken together, an alkene will decolourise bromine water, turning it from orange to colourless. This is because an addition reaction takes place where bromine is added across the alkene double bond.
Why doesn’t alkane react with bromine water?
As they don’t contain double bond
Can alkene react with steam?
Yes in addition reactions.
Which substance do alkene and alkanes burn?
Alkanes and alkenes burn in oxygen in combustion reactions.
What happens during the complete combustion?
They’re oxidised to from carbon dioxide and water
What happens if the alkenes and alkanes burn in a limited amount of oxygen?
You can get incomplete combustion
What are polymers?
Polymers are substances of high average relative molecular mass, made by joining up lots of small repeating units called monomers.
Why type of bonds do the addition polymers have?
The monomers that make up addition polymers have a double bond
How can polymer chains be formed?
Lots of unsaturated monomer molecules can open up their double bonds and join together to form polymer chains. This is called addition polymerisation .
What does the name of the polymer come from?
The name of the polymer comes from the type of monomer it’s made from- you just put brackets around it and stick the word ‘poly’ in front of it.
What would propene become (as a polymer) ?
Propene would become poly(propene)- same with the others.
How would you get the formula of a polymer?
You just put the formula of the monomer in brackets and put a little n after it.
How can you draw the displayed formula of an addition polymer from the displayed formula of its monomer?
1) Join the carbons together in a row with no double bonds in between them, stick a pair of brackets around the repeating bit and put a ‘n’ after it ( to show there are lots of monomers)
2) You should also draw a bond from each of the two carbons in the chain that pass through the bracket- this shows that the chain continues.
How can you draw the displayed formula of the monomer from the displayed formula of the polymer?
1) Draw out the repeating bit of the polymer , get rid of the two bonds going out through the brackets and put a double bond between the carbons.
What do the properties of polymers depend on?
The properties on the arrangement of the polymer chains and their forces between them.
What are a few examples of addition polymers?
- Poly(tetrafluroethene)- PTFE
- Poly(chloroethene)- PVC
- Poly(ethene)
- Poly (propene)
What does each polymer have?
Each polymer has it’s own set of properties.
What is a property of poly(ethene)?
- Flexible
- electrical insulator
- cheap
What is a use of poly(ethene)?
- Plastic bags
- Bottles
- Wire insulation
What is a property of Poly (propene)?
- Flexible
- Strong
- Tough
- Mouldable
What is a use of Poly (propene)?
- Crates
- Furniture
- Ropes
What is a property of Poly(chloroethene)- PVC?
- Tough
- Cheap
What is a use of Poly(chloroethene)- PVC?
- Window frames
- Water pipes
What is a property of Poly(tetrafluroethene)- PTFE?
- Unreactive
- Tough
- Non-stick
What is a use of Poly(tetrafluroethene)- PTFE?
- Non-stick pans
- Waterproof clothes
How can condensation polymerisation be made by polymers?
PROCESS
1) Condensation polymers usually involve two different types of monomer.
2) The monomers react together and bonds form between them, making polymer chains.
3) Each monomer has to contain at least two functional groups, one on each end of the molecule.
4) Each functional group can react with the functional group of another monomer, creating a long chains of alternating monomers.
What happens when new bonds form?
for the condensation polymer process
For each new bond that forms, a small molecule (e.g. water) is lost.
How do polyesters form?
Polyesters form when dicarboxylic acid monomers and diol monomers react together.
What does the dicarboxylic acid monomer contain?
Two carboxylic (-COOH) acid
What does the diol monomer contain?
Two alcohol (-OH) groups
What happens when the carboxylic acid group react with the alcohol group?
It forms an ester link
How are polyesters condensation polymers?
As each time an ester link is formed, a molecule of water is lost.
Give examples of polymers that occur naturally:
DNA
Protein
What is DNA?
- Complex molecule that contains genetic information
- Contains 2 strands made from nucleotides that bond together in a polymerisation reaction
- DNA is made from four different monomers (nucleo tide)
What do the amino acids form?
- Amino acids monomers for polymers known as proteins via condensation polymerisation
- Proteins have an important role in the body
What are carbohydrates?
Molecules containing carbon, oxygen and hydrogen, used by living things to produce energy
- Starch and cellulose are large, complex carbohydrates, which are made up of many smaller units of carbohydrates known as sugars joined together in a long chain.
What is plastic?
Plastics are a type of polymer made from crude oil
Why will the price of crude oil increase?
The more we use up the crude oil ,the more expensive crude oil will become
What is crude oil used?
Petrol for cars and heating for homes
How can we solve the problem of resources drying up?
Recycling
How many tonnes of plastic is generated per year?
2 million tonnes
Describe the disposal of polymers in landfill sites process?
1) Lot of plastic is dumped on landfill sites. This is usually when the plastic is difficult/ expensive to recycle.
2) Lots of valuable land is getting used up for landfill sites
3) Most polymers are non-biodegradable- they’re not broken down by micro organisms. This means they will sit in landfills for years.
Describe the disposal by combustion process:
1) Burning plastics produces lots of energy and this can be used togenerate electricity
2) If not controlled toxic gases can be produced. For example when polymers containing chlorine burn they produce HCL- this has to be removed
3) CO2 is also produced, contributes to global warming.
What does recycling polymers do?
Limits the amount of crude oil we’re using
What are the advantages of recycling?
- Reduces the mount of non biodegradable waste on landfill sites
- Reduces emissions of greenhouse and toxic gases
- Uses less water and energy resources when making new plastics
- Reduces the amount of crude oil we need
- saves money and creates jobs
What are the disadvantages of recycling?
- Polymers must be separated before they can be melted and reformed- this can be expensive
- If polymers are mixed together the quality of the final polymer could be reduced
- Polymers can only be reduce3d for a finite amount of times. Over time the strength decrease.
- Melting polymer release dangerous toxins. Harmful to plants and animals
What is the general formula for an alcohol?
Cn2n+1
What do all alcohols contain?
An -OH functional group
What is the formula for methanol?
CH3OH
What is the formula for ethanol?
C2H5OH
What is the formula for propanol?
C3H70H
What is the formula for butanol?
C4H9OH
What do alcohol form when they’re oxidised??
Carboxylic acids- You need an oxidising agent for this
What is the naming system for Carboxylic acids?
Replace the ending with -‘oic acid’
What are Carboxylic acids
Another homologous series of molecules
What is the general formula of Carboxylic acids?
Cn-1 H2n-1 COOH
How can the firs four Carboxylic acids be formed?
They can be formed by oxidising the alcohol which contains the same total of carbons
What is the formula for methanoic acid?
HCCOH
What is the formula for ethanoic acid?
CH3COOH
What is the formula for propanoic acid?
C2H5COOH
What is the formula for BUTANOIC AICD?
C3H7COOH
What is fermentation?
Fermentation is the process of using yeast to convert a type of carbohydrate called surgas into alcohol
What is the formula for fermentation?
C6H12O6——-> 2C2H5OH + 2 CO2
glucose—-> ethanol + carbon dioxide.
Where does the carbohydrate come from?
The carbohydrate can come from any source but the sugar cane and sugar beet plants are often used
Describe how you would use alcohol as a fuel:
*experiment
1) Put some alcohol into a sprit burner and measure the mass of burner
2) Measure 100 cm3 distilled water into a copper calorimeter
3) Insulate calorimeter by using draught excluder, then cover with insulating lid after placing a thermometer inside. Reduce energy loss
4) Ttake initial temp of water then put burner under calorimeter and light the wick
5) Stir water . When the temp rises to 2o degrees blow out sprit burner.
6) Immediately reweigh burner and fuel
7) Repeat experiment with different alcohols.
How would make ethanol by fermentation?
Mix yeast and a solution of carbohydrates in a clean container. Seal the container and leave it in a warm place .
keep the mixture in between 30.40° c-fermentation happens fastest between these temperatures. At lower temperature the reaction slows down. If it’s too hot the enzymes in the yeast denature and the reaction would stop.
Important to help the mixture in anaerobic respiration as oxygen converts ethanol to etnanoic acid.
when concentration of alcohol reaches about 10% or2o%the fermentation reaction stops because the yeast gets killed off by the alcohol.
The yeast will fall tot he bottom of the container. You can collect the ethanol solution from the top.
Describe how you would use alcohol as a fuel:
*experiment
1) Put some alcohol into a sprit burner and measure the mass of burner
2) Measure 100 cm3 distilled water into a copper calorimeter
3) Insulate calorimeter by using draught excluder, then cover with insulating lid after placing a thermometer inside. Reduce energy loss
4) Take initial temp of water then put burner under calorimeter and light the wick
5) Stir water . When the temp rises to 2o degrees blow out sprit burner.
6) Immediately reweigh burner and fuel
7) Repeat experiment with different alcohols.
What do different polymers have?
Different physical properties- some are stronger, stretcher easily moulded
What do poly (ethene) make?
Strong, rigid used to make water pipies
What do light strechy poly ethene make?
Pplastic bags
What do poly (ethene) make?
Strong, rigid used to make water pipes
What do light strechy poly ethene make?
Plastic bags
Wwhat is clay
- Mineral formed from weathered and decomposed rocks
- Soft when dug up of ground, makes it easier to mould
Wwhat is clay
- Mineral formed from weathered and decomposed rocks
- Soft when dug up of ground, makes it easier to mould into different shapes or bricks
- Can be hardened by firing it a high temp. Makes it an ideal building material- clay bricks can withstand weight of more bricks on top of them
What is glass?
- Transparent strong
- Can be moulded when hot and brittle when thin
- Majority of glass is soda lime- made by heating limestone, sand and sodium carbonate until they meLT. wHENCOOLS BECOMESGLASS
What are fibreglass and concrete made out of?
One material embedded in another- known as composites
What is the properties of composites?
Depends on the properties its made from
What are carbon fibre composites?
Made using carbon atoms bonded together to make carbon fibres held in a polymer resin matrix.
Expensive to make but are string
How are the polymers suited for , their job?
- Often flexible, so they can bend without breaking and can be easily moulded into almost any shape.
- Cheaper than other materials
- Less dense than ceramics
- Thermal and electrical insulTORS.
- Can degrade and break down overtime so don’t last long
How are ceramics suited for their jobs?
- Insulators of heat and electricity
- More brittle and stiff
- String and hard wearing
- Don’t degrade or corrode like other materials
- Last longer which is why I glass is used for windows instead of plastics
How are metals suited to their job?
- Good conductors of heat and electricity
- Malleable like polymers, can be formed into different shapes.
- Some corrode easily
- Corrosion resistant metals last long
- Less brittle than ceramics
How are composites suited to their jobs?
- Different properties depending on matrix/binder and reinforcement/
- More expensive.
Describe how to make ethanol by distillation:
The fermented mixture can be distilled to produce more concentrated alcohol.
1) A dilute solution of ethanol is produced by fermentation.
2) To make a concentrated of ethanol above 20%, ethanol must be concentrated by fractional distillation of the fermentanion mixture.Fractional dimidiation separates mixtures by heating them
3) Ethanol has al ower boiling point than water. This means the ethanol will evaporate and the vapour will rise while he water stays as a liquid
4) A condenser is used to condense the ethanol vapour
Why can alcoholsbe sued as fuels?
can be used as a fuel as when they’ re burned they release energy
countries have no oil diposists, so grow sugar canes and use ethanol as a fuel.
