Year 10 Term 2 Flashcards
What are the intermolecular forces like between smaller molecules
They are weaker so less energy is needed to break them
What are the intermolecular forces like between larger molecules
They are stronger and more energy is needed to break them
Fractions that have a low boiling point…
…evaporate easily. The earlier a fraction evaporates, the more volatile it is
What does volatile mean
How quickly it reacts with oxygen
What happens when fractions burn
They react with oxygen in the air, the more volatile it is the quicker it mixes with air
What’s viscosity
A resistance to flow
The longer the hydrocarbon, the more viscous it is
What does the colour of a faction depend on and what happens when the molecules get smaller
Depends on size of molecules it contains
As molecules get smaller, colour gets lighter
What’s cracking hydrocarbons
Breaking down larger hydrocarbons into smaller ones
What’s thermal cracking
Long hydrocarbon chains are vaporised
Placed under high temp and pressure
Long chains ‘cracked’ as thermal decomposition takes place
Large chains split into smaller, more useful ones
Problems with thermal cracking
Doesn’t have much control over what products are made
Getting to high temps is expensive
Cost ineffective
What’s catalytic cracking
Long hydrocarbon chain vaporised and passed over catalyst
Heated to high temp
Long chains cracked as thermal decomposition takes place
When is catalytic used and what does it produce
Used in industry splits mostly between 8 and 10 carbons in length
Chains of this length are used for petrol
What’s an alkene
Family of hydrocarbon compounds with general formula CnH2n
Used to make plastics and other chemicals
Contain a double carbon to carbon bond
Simplest alkene with formula
Ethene C2H4 H H | | C=C | | H H
Second simplest alkene with formula
Propene C3H6
H H H
| | |
H —C—C=C
| |
H HThird simplest alkene with formula
Butene C4H8
H H H H
| | | |
H —C—C—C=C
| | |
H H HFourth simplest alkene with formula
Pentene C5H10
H H H H H
| | | | |
H —C—C—C—C=C
| | | |
H H H HWhat’s a saturated compound and give example
Only contains single covalent bond between carbon atoms
Alkanes
What’s an unsaturated compound and give example
Contains at least one double covalent bond between carbon atoms
Alkenes
Why is there no methene
Because alkenes need a double carbon-carbon bond and methene doesn’t have this
How do you test for alkenes
Will turn bromide water from orange to clear
What’s a formulation
Mixture of compounds/substances that don’t react with each other but produce a mixture with the desired properties to suit a particular application or use
Examples of formulations
Fertiliser Petrol Makeup Paint Medicine Alloys
What’s chromatography
Separating mixtures into their components in order to analyse, identity, purify and quantify the mixtures or components
What’s the mobile phase
The solvent that moves up the paper
What’s the stationary phase
The paper
How do you work out the Rf factor
Distance moved by substance / distance moved by solute
How to test for hydrogen
Add 2cm^3 of HCL to test tube
Add strip of magnesium to test tube
Light splint with Bunsen and place in test tube squeaky pop test
Equation for hydrogen test
Magnesium + HCL —> magnesium chloride + hydrogen
How to test for carbon dioxide
Put 5cm^3 HCL in test tube and 10cm^3 limewater in another
Put 2 spatulas powered calcium carbonate to HCL and quickly add stopper
Put delivery tube in limewater
Equation for carbon dioxide test
Calcium carbonate + HCL —>calcium chloride + carbon dioxide + water
How to test for oxygen
Put 2cm^3 hydrogen peroxide into test tube
Add 1 spatula of powdered manganese oxide
Light splint then blow out so still glowing
Place glowing splint in test tube
Equation for oxygen test
Hydrogen peroxide —> water + oxygen
What are the two ways to test for positive ions
Flame test
Sodium hydroxide test
Flame test for positive ions
Take splint and dip into 1 of 6 solutions
Hold in hottest part of flame observing any colour change
Sodium hydroxide test for positive ions
Take test tube add 1cm^3 of one of the 6 solutions
Add 1cm^3 of NaOH solution
Observe and record any changes
If precipitate white add another 5cm^3 of NaOH solution
Observe and record any changes
What’s flame emission spectroscopy
instrumental method used to analyse metal ions in solutions
how does flame emission spectroscopy work
sample put into a flame and the light given out is passed through a spectroscope that’s analysed to identify metal ions in solution and measure concentrations
advantages of flame emission specroscopy
very quick
accurate
sensitive-only requires small sample
brightness of spectrum determines concentration sample
disadvantages of flame emission spectroscopy
destructive-the sample being tested is burned
only identifies elements, not compounds
what is flame emission spectroscopy used for
quality control in chemical manufacture
working out the composition of distant stars
