mistake log

what separating technique is used to separate ethanol and water and why?

fractional distillation - their boiling points are relatively close together

what are the advantages of having a lid for volatile and flammable solutions?

no risk of fire

solution won’t evaporate

fumes may be poisonous/toxic

what is the filtrate?

the liquid you obtain from flitration

what substances are needed for iron to rust?

oxygen and water

give an example of galvanising

a bucket

why are results in rate of reaction experiments least accurate at higher temperatures?

reaction occurs very quickly so is difficult to time

heat loss is greater, so it is difficult to keep temperatures constant

how do we draw poly(propene)?

basically the same as poly(ethene) however the key point is to remember that you don’t draw the chain length as three, instead you just add a CH₃ to the two carbons instead of a hydrogen

define the term biodegrade

broken down/decomposed by bacteria

identify the property that prevents addition polymers from easily biodegrading?

inert

when you’re naming C₄H₈ what are you going to remember to do?

check displayed formula to see if it’s but-1-ene or but-2-ene (remember it’s where the double bond is - if the other two carbons are attached to one of the carbons in the double bond, it’s but-1-ene, if there’s one on each it’s but-2-ene

why is it important to crack long chain hydrocarbons?

greater supply of long chain hydrocarbons

more demand for short chain hydrocarbons

short chain hydrocarbons used as fuels

how does the covalent bonding differ in crude oil and kerosene?

more covalent bonds in crude oil

(bonus point if you’re doing a differences question - crude oil is darker, more viscous and has (on average) larger molecules

why is ethanol sometimes made by fermentation not by hydration of ethene?

sugar cane is a renewable resource

temperature is lower in fermentation, so uses less energy

why might it be better to burn plastic bags which aren’t biodegradable?

space in landfill not taken up

provides heat

why might it be better to bury plastic bags which don’t biodegrade?

not produce greenhouse gases

doesn’t contribute to global warming

doesn’t pollute the soil

why does the (platinum) wire need to be cleaned between each flame test?

to remove any substance which might affect the colour

why is it important that the platinum wire is clean for flame test?

impurities may affect colour of sample

what should you add to a solution to react with any carbonate ions which may be present?

hydrochloric acid

what are two observations made when sulfuric acid is added to iron

fizzing

iron disappears

suggest what property of hydrogen makes it good for filling balloons

low density

suggest what property of helium makes it the most suitable for filling balloons

non-flammable

why shouldn’t you heat a solution until all the water boils off if you’re making crystals?

boiling off all water will not produce a hydrated salt

what are you going to think about when it’s asking for mistakes in a method?

whether the reactants make the correct product

whether something is soluble or insoluble

if you use a burette and there’s some air between the tap of burette and tip how will it affect the calculated result?

calculated volume will be higher as it includes the air