Year 10 Term 2
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
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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 H
Third simplest alkene with formula
Butene C4H8 H H H H | | | | H —C—C—C=C | | | H H H
Fourth simplest alkene with formula
Pentene C5H10 H H H H H | | | | | H —C—C—C—C=C | | | | H H H H
What’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