Paper 2 stuff :) Flashcards
concentration =
moles/ volume
Volume =
moles x 24
What are titrations used for?
finding out exactly how much acid is needed to neutralise a quantity of alkali
Explain the process of a titration?
- using a pipette and pipette filler add some alkali to a conical flask along with two or three drops of indicator
- fill a burette with acid, making sure its done at eye-level
- use burette, add acid to alkali a bit at a time giving conical flask a swirl
- the indicator changes colour when all the alkali has been neutralised
- record volume of acid needed to neutralise acid. repeat this to check results
How do you make insoluble salts?
precipitation experiment, using two soluble salts
What two things are needed to make lead sulfate?
lead nitrate and magnesium sulfate
What is solubility?
a measure of how much solute will dissolve in a solvent
What is solubility measured in?
grams of solute per 100 grams of solvent
How does temperature effect solubility?
increases solubility
What can you use a solubility curve for?
to see the solubility of a substance at a specific temperature
What is the solubility equation?
solubility = mass of solid / mass of water removed x100
Explain how you would investigate how the solubility of ammonium chloride is effected by temperature?
- make a saturated solution by adding excess of ammonium chloride to 10cm cubed of water to a boiling tube
- stir and place in water bath at 25C
- after 5 mins check that all of the excess solid has sunk to the bottom of the tube and check solution is at 25C
- weigh empty evaporating basin, pour some solution on (no undissolved solid)
- reweigh basin and contents then gently heat using bunsen burner until all water removed
- reweigh evaporating basin and contents
- repeat at two more temperatures
- plot results
What are ions?
charged particles
What structure do ionic compounds have?
lattice structure/ giant ionic structures
Descibe ionic compounds?
- ions held together in closely packed 3D lattice by strong electrostatic attraction between oppositely charged ions
- high melting and boiling points
- not electrical conductors when solid, if you melt or dissolve them in water they are able to conduct electricity
Define a covalent bond?
strong electrostatic attraction between the negatively charged shared electrons and the positively charged nuclei of the atoms involved
What are the features of a simple molecular structure?
- atoms within molecule held together by strong covalant
- forces of attraction between molecules are very weak
- feeble intermolecular forces
- low melting and boiling due to weak intermolecular
- intermolecular forces are stronger with a high Mr
- usually gases or liquids
Describe giant covalant?
- no charged ions
- atoms bonded by strong covalent bonds
- high melting and boiling point
- insoluble in water
- dont conduct electricity
What is the reactivity series?
potassium sodium lithium calcium magnesium aluminium zinc iron copper silver gold
What is oxidation?
loss of electrons
what is reduction?
gain of electrons
How are most metals found?
in ores
What is the alcohol functional group?
OH
WHat is the alcohol general formula?
CnH2n+1OH
What are the first four alcohols?
methanol, ethanol, propanol, butanol
What can alcohols be oxidised to form?
carboxylic acids
What do you need to make carboxylic acids?
potassium dichromate in dilute sulfuric acid
What is formed when ethanol is heated with potassium dichromate in dilute sulfuric acid?
ethanoic acid
What forms carboxylic acids from alcohol?
microbial oxidation
Explain microbial oxidation?
some microorganisms are able to use alcohols as an energy source. to do this they used oxygen in the air to oxidise alcohols
carboxylic acids are made as a by product of this
When alcohols are burned what happens?
they are oxidised
What happens when alcohols are burned in enough oxygen?
undergo complete combustion
What is complete combustion of alcohols equation?
ethanol + oxygen –> carbon dioxide + water
What are the two ways of producing ethanol?
- ethene and steam
- fermentation
Explain ethanol production from ethene and steam?
- ethene is produced from crude oil
- ethene reacts with steam to form ethanol - addition reaction
- temp is 300 and pressure is 60-70 atmospheres
- phosphoric acid used as catalyst
What are the benefits and drawbacks of producing ethanol from ethene and steam?
- cheap process becuase ethene is cheap and not wasted
- crude oil is non- renewable which means it will start running out - could become expensive
fermentation equation?
C6H1206 —> 2C2H5OH + 2CO2
Explain fermentation method?
- raw material of sugar (glucose) is converted to ethanol using yeast
- yeast cells contain enzymes- naturally occuring catalysts
- 30C to optimise rate but not denature enzymes
- keep in anaerobic conditions so that the ethanol isnt converted to ethanoic acid
What are the advantages to fermentation?
- raw materials are all from renewable source
- sugar is grown in crops around world and yeast is easy to grow
What are the disadvantages of fermentation?
- ethanol isnt very concentrated so needs to be distilled to increase strength and needs purifying
equation for ethene and steam?
C2H4 + H20 —> C2H5OH
Explain steps in finding out concentration of acid in titration?
- work out moles of known substance
- write out equation and compare ratio
- use concentration formula
What is a metal ore?
if a compound contains enough of metal worth extracting
If a metal is more reactive, is it harder or easy to extract?
harder
What type of reaction is usually used for extraction?
reduction reaction
What is the problem with reduction reactions with carbon?
only metals that are less reactive then carbon can be extracted
How are elements more reactive then carbon extracted?
using electrolysis
What is electrolysis?
using electricity to extract a metal
Explain steps in working out water of crystalisation?
- work out mass of all substances
- calculate number of moles of water lost
- calculate moles of anhydrous salt
- work out ratio of salt to water
- whole number
Explain diamond structure?
- network of carbon atoms that each form four covalant bonds
- strong covalant bonds mean high melting point
- strong bonds mean rigid lattice structure so hard
- no delocalised electrons so doesnt conduct
Explain graphite?
- each carbon forms three covalant creating layers of carbon atoms
- layers have weak intermolecular forces so slide over each other making it soft and slippery
- high melting point due to covalant bonds in layers
- only three out of carbon four outer electrons are used so one delocalised to conduct electricity
Explain C60 fullerene?
- hollow sphere of 60 carbon atoms
- made of large covalent molecules
- weak intermolecular forces so can slide over eachother making it soft
- one delocalised electron but electrons can move between molecules so poor conductor
WHat is electric current?
flow of electrons or ions
What happens when electrons or ions move?
cause material they are in to conduct electricity
Do solid ionic compounds conduct electricity?
no - ions can move around
Explain why ionic compounds can conduct electricity as a solution?
- when dissolved the ions are separate and are able to move in the solution
Explain why ionic compounds can conduct in molten state?
when compound melts, ions are able to move and can conduct
What are metals held together by?
metallic bonding
Explain metal structure?
- giant structure of positive ions surrounded by sea of delocalised electrons
- electrostatic attraction between positive ions and electrons is called metallic bonding
Definition of metallic bonding?
electrostatic attraction between positive ions and the electrons
Why are most metals malleable?
- layers of ions in a metal can slide over each other making metals malleable, can be hammered or rolled into flat sheets
