Edexcel IAL Chemistry UNIT 3:Practical
How can you collect volume of gas? correct answers - Gas syringe
- Measuring cylinder upturned in water bath
Why do we extrapolate graphs to find maximum temperature? correct answers
Because reaction is not instantaneous so it may lose heat to surroundings, so we don't
know its true maximum temperature
The moles of which substance is used to caluculate heat transfer (Q=mcT) correct
answers moles of the limiting reactant
How do u find percentage uncertainty of an apparatus? correct answers 1/2 x
resolution
Why is a white tile placed under flask during titrations? correct answers To make it
easier to see colour change
Which solution goes into the burette during titration? correct answers Solution with the
known concentration
Which solution goes into conical flask during titration? correct answers Solution with
unknown concentration
Which solution is the titre? correct answers Solution with known concentration (from
burette)
What are concordant results? correct answers Results within 0.2 cm³ of each other
Why is the rough titre not used? correct answers It is not as accurate, only done to
know the rough volume needed
How do you prepare a standard solution? correct answers - Weigh out the correct mass
of solid (by difference) in a beaker.
- Add small volume of water and stir and dissolve.
- Transfer to standard volumetric flask and rinse beaker to ensure all solid is transferred.
- Fill up to 250cm³ mark
- Invert the flask to mix.
Why is a water bath used in hydrolysis of halogenoalkanes? correct answers Reaction
is too slow at room temperature
, How can you measure the rate of hydrolysis of halogenoalkanes? correct answers - Set
up 3 test tubes in 50C water bath
- Add ethanol and silver nitrate
- Add each type of halogenoalkane to each one
- Time how long it takes for precipitate to form
What colour are the halide precipitates? correct answers Chlorine - white
Bromine - cream
Iodine - yellow
Why does iodoalkane hydrolyses fastest? correct answers Because C-I bond is weaker
and breaks easiest
How do you carry out chlorination of 2-methyl propan-2-ol? correct answers - Measure
out 2-methylpropan-2-ol
-Pour into conical flask
- Add HCl acid and swirl
- Place a bung, swirl, remove
- 2 layers form, add CaCl2
- Transfer to separating funnel
- Run off lower aqueous layer
- Add NaHCO3
- Swirl and open bung
- Collect organic layer in a flask
- Add anhydrous sodium sulfate
- Distill liquid at 50-52C
Why is CaCl2 used? correct answers To ensure unreacted alcohol goes into lower
layre
Why is NaHCO3 used? correct answers To react with acid and remove acid impurities
Why is bung opened? correct answers To release pressure from CO2 produced
Why is anhydrous Na2SO4 used? correct answers It is a drying agent, removes any
water
How do you know that chlorination reaction is complete? correct answers Turns from
cloudy to clear
What safety precautions needed in chlorination? correct answers - 2 methylpropan2-ol
is flammable
- HCl is toxic, carry out in fume cupboard
- Wear gloves so reactancts don't contact skin
- CaCl2 is irritant
How can you collect volume of gas? correct answers - Gas syringe
- Measuring cylinder upturned in water bath
Why do we extrapolate graphs to find maximum temperature? correct answers
Because reaction is not instantaneous so it may lose heat to surroundings, so we don't
know its true maximum temperature
The moles of which substance is used to caluculate heat transfer (Q=mcT) correct
answers moles of the limiting reactant
How do u find percentage uncertainty of an apparatus? correct answers 1/2 x
resolution
Why is a white tile placed under flask during titrations? correct answers To make it
easier to see colour change
Which solution goes into the burette during titration? correct answers Solution with the
known concentration
Which solution goes into conical flask during titration? correct answers Solution with
unknown concentration
Which solution is the titre? correct answers Solution with known concentration (from
burette)
What are concordant results? correct answers Results within 0.2 cm³ of each other
Why is the rough titre not used? correct answers It is not as accurate, only done to
know the rough volume needed
How do you prepare a standard solution? correct answers - Weigh out the correct mass
of solid (by difference) in a beaker.
- Add small volume of water and stir and dissolve.
- Transfer to standard volumetric flask and rinse beaker to ensure all solid is transferred.
- Fill up to 250cm³ mark
- Invert the flask to mix.
Why is a water bath used in hydrolysis of halogenoalkanes? correct answers Reaction
is too slow at room temperature
, How can you measure the rate of hydrolysis of halogenoalkanes? correct answers - Set
up 3 test tubes in 50C water bath
- Add ethanol and silver nitrate
- Add each type of halogenoalkane to each one
- Time how long it takes for precipitate to form
What colour are the halide precipitates? correct answers Chlorine - white
Bromine - cream
Iodine - yellow
Why does iodoalkane hydrolyses fastest? correct answers Because C-I bond is weaker
and breaks easiest
How do you carry out chlorination of 2-methyl propan-2-ol? correct answers - Measure
out 2-methylpropan-2-ol
-Pour into conical flask
- Add HCl acid and swirl
- Place a bung, swirl, remove
- 2 layers form, add CaCl2
- Transfer to separating funnel
- Run off lower aqueous layer
- Add NaHCO3
- Swirl and open bung
- Collect organic layer in a flask
- Add anhydrous sodium sulfate
- Distill liquid at 50-52C
Why is CaCl2 used? correct answers To ensure unreacted alcohol goes into lower
layre
Why is NaHCO3 used? correct answers To react with acid and remove acid impurities
Why is bung opened? correct answers To release pressure from CO2 produced
Why is anhydrous Na2SO4 used? correct answers It is a drying agent, removes any
water
How do you know that chlorination reaction is complete? correct answers Turns from
cloudy to clear
What safety precautions needed in chlorination? correct answers - 2 methylpropan2-ol
is flammable
- HCl is toxic, carry out in fume cupboard
- Wear gloves so reactancts don't contact skin
- CaCl2 is irritant
