AS Depth chemistry paper H032/02
Name the apparatus that the student should use to:
- Make up the acid solution to 250.0cm3
-measure the 25.0cm3 portion of acid solution - ANS-volumetric flask
graduated pipette
the student is not confident that their titre is accurate
suggest what the student should do next to reduce the effect of any random error in the
titration - ANS-repeat titration until two titrations are concordant (0.01cm3 within)
calculate mean titre from concordant titres
describe how a sigma bond forms - ANS-sideways overlap of the orbitals between the
bonding atoms
state the bond angle and shape around each carbon atom of the C=C double bond in
propene - ANS-120degrees
trigonal planar
CH3CH2CH2CH=CH2
Pent-1-ene doesn't not show stereoisomerism explain why - ANS-One of the carbons In
the C=C has the same two groups bonded, so cannot form stereoisomers
The variation in boiling point can be explained by intermolecular bonding. explain
why H2S has a lower boiling point than H2O and H2Se - ANS-H2O has hydrogen
bonding that requires the most energy to overcome the hydrogen bonding. H2Se
and H2S both have induced dipole-dipole interaction.
But H2Se has a higher boiling point because it has more electrons so that more energy
is needed to overcome the induced dipole-dipole interactions in H2Se than H2S.
Predict the type of structure and bonding of SO2 and MgO and explain the difference in
their melting points - ANS-SO2 has covalent bonding and forms a simple molecular
lattice
MgO has ionic bonding and forms a giant ionic lattice
MgO has a higher melting point than SO2 due to the strength of the ionic bond
compared to intermolecular bonds in SO2.
MgO requires more energy to overcome/break than SO2's intermolecular forces
Name the apparatus that the student should use to:
- Make up the acid solution to 250.0cm3
-measure the 25.0cm3 portion of acid solution - ANS-volumetric flask
graduated pipette
the student is not confident that their titre is accurate
suggest what the student should do next to reduce the effect of any random error in the
titration - ANS-repeat titration until two titrations are concordant (0.01cm3 within)
calculate mean titre from concordant titres
describe how a sigma bond forms - ANS-sideways overlap of the orbitals between the
bonding atoms
state the bond angle and shape around each carbon atom of the C=C double bond in
propene - ANS-120degrees
trigonal planar
CH3CH2CH2CH=CH2
Pent-1-ene doesn't not show stereoisomerism explain why - ANS-One of the carbons In
the C=C has the same two groups bonded, so cannot form stereoisomers
The variation in boiling point can be explained by intermolecular bonding. explain
why H2S has a lower boiling point than H2O and H2Se - ANS-H2O has hydrogen
bonding that requires the most energy to overcome the hydrogen bonding. H2Se
and H2S both have induced dipole-dipole interaction.
But H2Se has a higher boiling point because it has more electrons so that more energy
is needed to overcome the induced dipole-dipole interactions in H2Se than H2S.
Predict the type of structure and bonding of SO2 and MgO and explain the difference in
their melting points - ANS-SO2 has covalent bonding and forms a simple molecular
lattice
MgO has ionic bonding and forms a giant ionic lattice
MgO has a higher melting point than SO2 due to the strength of the ionic bond
compared to intermolecular bonds in SO2.
MgO requires more energy to overcome/break than SO2's intermolecular forces
