paper 1 missed marks Flashcards
(27 cards)
what are the stages in a catalytic converter that decrease emissions of gases such as carbon monoxide?
CO molecules adsorbed onto the catalytic surface
which weakens the bonds
CO2 is desorbed from the catalytic surface
when would you expect ΔSsystem to be positive?
increase in number of moles from reactants to products
change of state from solid to liquid/gas/solution
explain how a buffer solution works
large reservoir of both acid and base/ the buffer (name them if poss)
OH- + HA —> A- + H2O
H+ + A- —> HA
because [H+] and [A-] are in such large amounts the [H+][A-] ratio barely changes so pH hardly changes
explain why the complex ions [Co(NH3)6]2+ and [Co(H2O)6]2+ are coloured and have different colours
d subshell splits into two different energies
difference in energy depends on the ligands
electrons undergo different d-d transitions requiring different energy
difference in energy leads to different frequencies
the unabsorbed frequencies are reflected
EDTA4- factfile
hexadentate
coordination number = 6
can form dative covalent bond with cobalt (III) ion
ethane-1,2-diamine factfile
bidentate
coordination number = 6
can form dative covalent bond with the cobalt (III) ion
explain why there is a difference in experimental lattice energy and theoretical lattice energy for MgI2?
some covalent character
magnesium ion is small and highly charged
iodide ion has a large ionic radius
iodide ion is polarised by the magnesium ion
make fc for hess cycles of hydration/solution!!
…
what does atomic emission spec provide evidence for?
quantum shells
what colour changes will be seen from universal indicator in a beaker of water containing water?
blue to purple
why do disproportionation reactions that aren’t feasible sometimes react to a small extent?
disproportionation is an equilibrium system
what type of reaction occurs when ammonia gas reacts with hydrogen chloride?
acid-base
colours of copper (II) chromate (VI) at the positive and negative electrodes
positive - yellow
negative - blue
why might a reaction carried out in a sealed container with a constant volume have different heat energy change to the enthalpy change?
system not at constant pressure due to gas produced increasing/changing the pressure
why can chromium show variable oxidation numbers? (in terms of ionisation energies)
steady increase in successive ionisation energies
potassium bromide and chlorine water equation
2KBr + Cl2 —> 2KCl + Br2
why is there no reaction between potassium bromide and iodine?
iodine cannot oxidise bromide ions
after using Q = mc^T what equation do you use to find enthalpy change?
^H = Q(in kJ) / number of moles
why is the standard enthalpy change of neutralisation of ethanoic acid with sodium hydroxide -55.2kJ/mol and the value of HCl -57.1 kJ/mol?
HCl is a strong acid so more energy is needed to ionoise the ethanoic acid
equation for decomposition of g1 compound NaNO3?
2NaNO3 —> 2NaNO2 + O2
equation of decomposition of a g2 nitrate?
2X(NO3)2 —> 2XO + 4NO2 + O2
why does magnesium carbonate decompose more readily on heating than barium carbonate?
Mg is smaller which polarises the carbonate ion and weakens the carbon-oxygen bond
equations for iron(II) catalysing 2I- + S2O8^2- —> I2 + 2SO4^2-
2Fe^2+ + S2O8^2- —> 2Fe^3+ + 2SO4^2-
2Fe^3+ + 2I- —> 2Fe^2+ + I2
equation for cobalt (II) catalysing SO3^2- + 1/2O2 —> SO4^2-
2Co^2+ + 1/2O2 + 2H^+ —> 2Co^3+ + H2O
2Co^3+ + SO3^2- + H2O —> 2Co^2+ + SO4^2- + 2H+
