Exam (elaborations)

IB Chemistry HL/SL paper two and biochemistry definitions

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Course
Chemistry

Institution
12th Grade

A compilation of IB Chemistry HL/SL definitions commonly asked on paper two and paper three for the biochemistry option B. Definitions are given with reference to the mark scheme definitions.

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Uploaded on June 27, 2023
Number of pages 5
Written in 2022/2023
Type Exam (elaborations)
Contains Questions & answers

ib chemistry
ib chemistry hl
ib chemistry sl
chemistry
chemistry hl
chemistry sl
ib biochemistry
biochemistry
higher level chemistry
standard level chemistry
definitions
ib
international baccalaureate

Institution Secondary school
Education 12th Grade
Course Chemistry
School year 1

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Topic 2 and 12
Describe how the relative atomic mass of a sample of calcium could be determined from its
mass spectrum
- Multiply relative intensity by m/z value of each isotope; find the weighted average
Outline the source of colours and why they are different for different elements
- Promoted electrons are relaxed to lower energy levels; different because the
difference between energy levels is different for different elements

Topic 3 and 13
Outline what would happen to the wavelengths at which the vanadium complex ions would
absorb light as the water molecules are gradually replaced with chloride ions
- Cl- is a weaker ligand; absorption wavelength increases
Outline why there is an increase in ionization energy
- As more electrons are removed, the pull of the nucleus / positive ions holds the
remaining electrons more tightly
Explain the large increase in ionization energy for V
- 5th electron is lost from the valence shell
- 6th electron is lost from a complete inner shell
- The inner shell is less well shielded / closer to the nucleus
Describe the trend in acid-base properties of the oxides of period 3
- Basic to acidic; through amphoteric
Explain the decrease in atomic radius from Na to Cl
- Nuclear charge increases to electrons are pulled more closely to the nucleus
- Elements in the same energy level so similar shielding
Explain why Na+ has a smaller ionic radius that O2-
- Same electron configuration; Na+ has more protons
Outline why chlorine has a smaller atomic radius than sulfur
- Occupy the same number of energy levels / have similar shielding; chlorine has one
more proton causing a stronger pull on the electrons
Explain why a copper (II) solution is blue
- Orange light is absorbed «and the complementary colour is observed»
- Any TWO from: partially filled d-orbitals / «ligands/water cause» d-orbitals «to» split
/ light is absorbed as electrons move to a higher energy orbital «in d–d transitions»
OR light is absorbed as electrons are promoted / energy gap corresponds to «orange»
light in the visible region of the spectrum

Topic 4 and 14
State what is meant by resonance
- More than one possible position for a pi bond
Describe the nature of ionic bonding
- Lattice; electrostatic attractions between oppositely charged ions
Suggest why a three-membered ring is unstable
- The bond angle is 60 / strained
Describe the bonding in metals

, - Electrostatic attractions; lattice of positively charges ions AND sea of delocalized
electrons

Topic 5 and 15
Predict whether Mn2+ or Fe2+ s more likely to have a more exothermin enthalpy of
hydration
- Fe2+ because it has a smaller ionic radius; stronger interaction with water molecules

Topic 6 and 16
Explain how you attempt to confirm this rate expression, giving the results you would expect
- Test the effect on reaction rate by varying the concentrations of each reactant
independently; doubling [X] doubles rate, etc
Explain why a higher temperature causes the rate of reaction to increase
- Greater proportion of molecules have E ≥ Ea or E > Ea OR greater area under curve
to the right of the Ea; greater frequency of collisions «between molecules» OR more
collisions per unit time/second

Topic 8 and 18
Suggest why oxides of phosphorous are not major contributors to acid deposition
- Phosphorous is not commonly found in the air / low levels of phosphorous in the air
Outline one technique of pre and post-combustion methods to minimize sulphur dioxide
- Pre-combustion: remove sulphur-containing compounds
- Post-combustion: remove it by neutralization / reaction with alkaline
Suggest why it is more convenient to expressacidity using the pH scale rather than the
concentration of hydrogen ions
- Reduces a wide range of numbers to a small range OR simple/easy to use OR
converts exponential expressions into a linear scale/simple numbers

Topic 9 and 19
Oxidation is now defined in terms of change in oxidation number. Explore how earlier
definitions of oxidation and reduction may have led to conflicting answers.
- Oxygen gained so it could be oxidation; hydrogen also gained so it could be
reduction; oxidation increases so it must be oxidation

Topic 10 and 20
Phenylamine is produced by the reduction of nitrobenzene. Suggest how this conversion
could be carried out
- Heat with tin and HCl; aqueous alkali / OH-
When one enantiomer undergoes substitution by alkaline hydrolysis, approximately 75% of
the product molecules show inversion of configuration. Comment on the mechanisms that
occur
- Sn1 would give approximately 50% of each; so mechanism is a mixture of both Sn1
and Sn2

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