Edexcel A Level Chemistry (2024 Paper 3)
Exam Questions and Answers
what can heat help a solid do? - Answer>>dissolve
why should the volumetric flask be shaken when making a
standard solution? - Answer>>to ensure a uniform
concentration
why is a volumetric pipette more accurate than a measuring
cylinder? - Answer>>smaller uncertainty
if the burette isn't rinsed with the substance that will be put in it,
residual water might have what effect? - Answer>>dilute the
concentration leading to a larger titre
what is the problem with leaving the funnel in the burette? -
Answer>>small drops of liquid may fall from the funnel leading
to a lower titre volume
why is it okay to rinse with distilled water in a titration? -
Answer>>it doesn't add any extra mols of reagents
what can you do to decrease apparatus uncertainties? -
Answer>>decrease sensitivity uncertainty by using a greater
resolution or increase the size of the measurement
how would you reduce % uncertainty in a burette? -
Answer>>make the titre a larger volume by increasing conc and
vol of the substance in the conical flask or decreasing the conc of
the substance in the burette
how would you reduce % uncertainty in measuring mass? -
Answer>>use a balance that measures to more decimal places
, is water a poor or good nucleophile? - Answer>>poor
how does water react with halogenoalkanes - Answer>>slowly
in a substitution reaction
why does water go in the liebig condenser from the bottom? -
Answer>>to go against gravity allowing more efficient cooling
and preventing the backflow of water
why should electric heaters be used to heat organic substances?
- Answer>>highly flammable
why should a reflux condenser never be sealed? -
Answer>>build up of gas pressure could cause explosion
what are anti-bumping granules? - Answer>>prevent vigorous
uneven boiling by making small bubbles form instead of larger
bubbles
general method for purifying an organic liquid - Answer>>put
distillate of impure product into a separating funnel, was by
adding saturated NaCl, allow layers to separate then run off the
aq layer, run the organic layer into a dry conical flask and add
drying agent (eg anhydrous calcium chloride), carefully decant the
liquid into the distillation flask, distill to collect pure product
detailed method for preparing and purifying an ester -
Answer>>mix primary alcohol and carb acid, add conc sulphuric
acid drop by drop (to prevent uncontrolled boiling) and cool in a
water bath, when all acid has been added fit a reflux condenser to
the flask and gently heat the mixture over an electric heating
mantle, cool mixture and re-arrange apparatus for distillation,
shake distillate in separating funnel with NaCO3 soln releasing
the pressure at intervals, the lower aq layer is discarded, the
Exam Questions and Answers
what can heat help a solid do? - Answer>>dissolve
why should the volumetric flask be shaken when making a
standard solution? - Answer>>to ensure a uniform
concentration
why is a volumetric pipette more accurate than a measuring
cylinder? - Answer>>smaller uncertainty
if the burette isn't rinsed with the substance that will be put in it,
residual water might have what effect? - Answer>>dilute the
concentration leading to a larger titre
what is the problem with leaving the funnel in the burette? -
Answer>>small drops of liquid may fall from the funnel leading
to a lower titre volume
why is it okay to rinse with distilled water in a titration? -
Answer>>it doesn't add any extra mols of reagents
what can you do to decrease apparatus uncertainties? -
Answer>>decrease sensitivity uncertainty by using a greater
resolution or increase the size of the measurement
how would you reduce % uncertainty in a burette? -
Answer>>make the titre a larger volume by increasing conc and
vol of the substance in the conical flask or decreasing the conc of
the substance in the burette
how would you reduce % uncertainty in measuring mass? -
Answer>>use a balance that measures to more decimal places
, is water a poor or good nucleophile? - Answer>>poor
how does water react with halogenoalkanes - Answer>>slowly
in a substitution reaction
why does water go in the liebig condenser from the bottom? -
Answer>>to go against gravity allowing more efficient cooling
and preventing the backflow of water
why should electric heaters be used to heat organic substances?
- Answer>>highly flammable
why should a reflux condenser never be sealed? -
Answer>>build up of gas pressure could cause explosion
what are anti-bumping granules? - Answer>>prevent vigorous
uneven boiling by making small bubbles form instead of larger
bubbles
general method for purifying an organic liquid - Answer>>put
distillate of impure product into a separating funnel, was by
adding saturated NaCl, allow layers to separate then run off the
aq layer, run the organic layer into a dry conical flask and add
drying agent (eg anhydrous calcium chloride), carefully decant the
liquid into the distillation flask, distill to collect pure product
detailed method for preparing and purifying an ester -
Answer>>mix primary alcohol and carb acid, add conc sulphuric
acid drop by drop (to prevent uncontrolled boiling) and cool in a
water bath, when all acid has been added fit a reflux condenser to
the flask and gently heat the mixture over an electric heating
mantle, cool mixture and re-arrange apparatus for distillation,
shake distillate in separating funnel with NaCO3 soln releasing
the pressure at intervals, the lower aq layer is discarded, the
