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bond length in molecules such as ozone
bond order 1.5
resonance/delocalisation fo a pair of electrons
all bonds have the same length
explain the dependence of the dissociation of oxygen, O2 and ozone, O3 on the wavelength of UV radiation
a shorter wavelength of radiation/UV is needed to break the bond in O2
O2 has a stronger bond compared to ozone (bond order 2 vs bond order 1.5)
ozone absorbes longer wavelengths of radiation than oxygen
types of correlation
negative correlation = as one thing decreases, another thing increases
positive correlation = as one thing increases, another thing also increases
comment [based on a graph about a conclusion]
evidence may support claim but might not prove it
answer why evidence supports claim but what further evidence is needed to prove the claim
state one assumption made for calculations involving weak acids and their Ka values
assume that there is neglible dissociation of the acid
state the composition of a buffer solution
combine acid with similar concentration of its conjugate base
Explain why Cu2+ is coloured with reference to its electronic structure
Cu2+ has partially filled d-orbitals
d-orbitals split
light energy is absorbed as electrons are promoted to a higher energy level
the energy gap/light absorbed between teh d-orbitals corresponds to a wavelength of light in the visible region of the spectrum
compare and contrast the IMF that result in ethenone being less volatile than carbon dioxide
both have london dispersion forces (due to having same number of electrons/similar Mr)
ethenone has dipole-dipole forces and carbon dioxide does not (due to C-H bond)
state one reason why gases become less ideal at higher pressures/lower temperatures
high pressure - gas particles are closer together and are influenced by forces of attraction therefore IMF are no longer neglible
low temperature - particles have lower kinetic energy, greater opportunity for IMF to have an effect and therefore they are no longer neglible
outline how two enantiomers can be distnguished
using a polarimeter
the enantiomers will rotate a plane of polarised light by the same angle but in opposite directions
explain why increasing the temperature increases the rate of a chemical reaction
more particles possess the necessary activation energy
more particles with E>Ea
frequency of collisions increases
more successful collisions per unit time
state the reagent for the conversion of the compound C3H8O into C3H6O
K2Cr2O7 and acidified/H+
explain why the compound C3H8O has a higher boiling point than C3H6O
hydrogen bonding is stronger than dipole-dipole
C3H8O has hydrogen bonding whilst C3H6O doesn’t
outline two laboratory methods of distniguishing between solutions of citric acid and hydrochloric acid of equal concentration, stating the expected observations
hydrochloric acid will react faster and with more effervescence with a reactive metal than citric acid
hydrochloric acid will conduct electricity better than citric acid
[citric acid has a higher pH because it is a weaker acid]
Describe using a suitable equation how the buffer solution formed during the titration resists pH changes when a small amount of acid is added
equilibrium shifts to the ethanoic acid side
CH3COOH/CH3COO- ratio virtually/mostly unchanged
[added acid is neutralised by ethanoate ions]
state the electronic configuration of the Cu+ ion
1s22s22p63s23p63d10
[normal Cu atom has 4s1 subshell]
Describe how the blue colour is produced in the Cu(II) solution
ligands cause d-orbitals to split
light absorbed as electrons are promoted to a higher energy level
energy gap corresponds to orange lift in the visible region of spectrum
colour observed is complementary to the colour absorbed - blue
Deduce why the Cu(I) solution is colourless
full 3d sublevel/orbitals (3d10)
Examine the relationship between the Bronsted-Lowry and Lewis definitons of a base referring to the ligands in the complex ion [CuCl4]2-
ligand/chloride ion is a Lewis base as it donates an electron pair
chloride ion is not a Bronsted-Lowry base as it does not accept a proton
Lewis base definition is broader/extends further than the Bronsted Lowry definition