A Level OCR A -Chemistry Paper 3 Test With Verified
d d d d d d d d d d
Solutions
Amount of substance equations - ANSWER:mass = mr x moles
d d d d d d d d d
mol = vol x conc
d d d d
vol(gas) = mol x 24 (dm)
d d d d d
PV=nRT
(pressure, Pa, volume, m3, moles, -, 8.314, temp, k)
d d d d d d d d
Empirical formula - ANSWER:The simplest whole number ratio of atoms of each element in a
d d d d d d d d d d d d d d d
compound
Molecular formula - ANSWER:The number and type of atoms of each element in a molecule
d d d d d d d d d d d d d d
Celsius to Kelvin - ANSWER:K=C+273
d d d d
% yield and atom economy - ANSWER:% yield = (actual/ theoretical) x 100
d d d d d d d d d d d d
,atom economy = (desired products/all reactants) x 100
d d d d d d d
Oxidising agent - ANSWER:it itself is reduced, causes another species to be oxidised
d d d d d d d d d d d d
Reducing agent - ANSWER:it itself is oxidised, causes another species to be reduced
d d d d d d d d d d d d
Oxidation - ANSWER:Loss of electrons, increased oxidation number
d d d d d d d
Reduction - ANSWER:Gain in electrons, decreased oxidation number
d d d d d d d
Balancing half equations - ANSWER:Balance all atoms apart from oxygen and hydrogen
d d d d d d d d d d d
Add H2O to balance oxygen
d d d d
Add H+ to balance hydrogen
d d d d
Add e- to balance charges
d d d d
Potassium manganate and iron ions [or (COOH)2] titrations - ANSWER:Potassium manganate
d d d d d d d d d d d
reduced (burette) d
Iron solution + excess dilute H2SO4 (provides H+ ions)
d d d d d d d d
added to conical flask (colourless)
d d d d
doesnt need indicator (self indicating)
d d d d
end point = permanent pink colour
d d d d d
Fe2+ --> Fe3+ + e-
d d d d
MnO4- + 8H+ + 5e- --> Mn2+ + 4H2O
d d d d d d d d
MnO4- + 8H+ + 5Fe2+ --> Mn2+ + 4H2O + 4Fe3+
d d d d d d d d d d
, Iodine and sodium thiosulfate titrations - ANSWER:Na2S2O3 oxidised (burette)
d d d d d d d d
oxidisng agent + excess KI produces iodine in conical flask (yellow-brown)
d d d d d d d d d d
titration --> pale straw colour d d d d
add starch indicator (end point= blue-black --> colourless)
d d d d d d d
I2 + 2e- --> 2I-
d d d d
2S2O3 2- --> S4O6 2- + 2e- d d d d d d
2S2O3 2- + I2 --> S4O6 2- + 2I-
d d d d d d d d
ClO- content in bleach - ANSWER:ClO- reacts w/ I- and H+ to form I2, then titrated
d d d d d d d d d d d d d d d
Cu2+ content in copper (II) compounds - ANSWER:For copper (II) salts, dissolve in water to form
d d d d d d d d d d d d d d d
Cu2+ ions
d d
For insoluble copper (II) compounds, react w/ acid acid to form Cu2+
d d d d d d d d d d d
For copper alloys (e.g. brass or bronze), dissolve in conc. nitric acid then neutralise to form
d d d d d d d d d d d d d d d d
Cu2+ d
Cu2+ + I- --> I2 + CuI
d d d d d d d
(overall brown coloured mixture) d d d
Voltaic cell - ANSWER:Converts chemical energy to electrical energy
d d d d d d d d
Made by connecting 2 different half cells, allowing electrons to flow
d d d d d d d d d d
d d d d d d d d d d
Solutions
Amount of substance equations - ANSWER:mass = mr x moles
d d d d d d d d d
mol = vol x conc
d d d d
vol(gas) = mol x 24 (dm)
d d d d d
PV=nRT
(pressure, Pa, volume, m3, moles, -, 8.314, temp, k)
d d d d d d d d
Empirical formula - ANSWER:The simplest whole number ratio of atoms of each element in a
d d d d d d d d d d d d d d d
compound
Molecular formula - ANSWER:The number and type of atoms of each element in a molecule
d d d d d d d d d d d d d d
Celsius to Kelvin - ANSWER:K=C+273
d d d d
% yield and atom economy - ANSWER:% yield = (actual/ theoretical) x 100
d d d d d d d d d d d d
,atom economy = (desired products/all reactants) x 100
d d d d d d d
Oxidising agent - ANSWER:it itself is reduced, causes another species to be oxidised
d d d d d d d d d d d d
Reducing agent - ANSWER:it itself is oxidised, causes another species to be reduced
d d d d d d d d d d d d
Oxidation - ANSWER:Loss of electrons, increased oxidation number
d d d d d d d
Reduction - ANSWER:Gain in electrons, decreased oxidation number
d d d d d d d
Balancing half equations - ANSWER:Balance all atoms apart from oxygen and hydrogen
d d d d d d d d d d d
Add H2O to balance oxygen
d d d d
Add H+ to balance hydrogen
d d d d
Add e- to balance charges
d d d d
Potassium manganate and iron ions [or (COOH)2] titrations - ANSWER:Potassium manganate
d d d d d d d d d d d
reduced (burette) d
Iron solution + excess dilute H2SO4 (provides H+ ions)
d d d d d d d d
added to conical flask (colourless)
d d d d
doesnt need indicator (self indicating)
d d d d
end point = permanent pink colour
d d d d d
Fe2+ --> Fe3+ + e-
d d d d
MnO4- + 8H+ + 5e- --> Mn2+ + 4H2O
d d d d d d d d
MnO4- + 8H+ + 5Fe2+ --> Mn2+ + 4H2O + 4Fe3+
d d d d d d d d d d
, Iodine and sodium thiosulfate titrations - ANSWER:Na2S2O3 oxidised (burette)
d d d d d d d d
oxidisng agent + excess KI produces iodine in conical flask (yellow-brown)
d d d d d d d d d d
titration --> pale straw colour d d d d
add starch indicator (end point= blue-black --> colourless)
d d d d d d d
I2 + 2e- --> 2I-
d d d d
2S2O3 2- --> S4O6 2- + 2e- d d d d d d
2S2O3 2- + I2 --> S4O6 2- + 2I-
d d d d d d d d
ClO- content in bleach - ANSWER:ClO- reacts w/ I- and H+ to form I2, then titrated
d d d d d d d d d d d d d d d
Cu2+ content in copper (II) compounds - ANSWER:For copper (II) salts, dissolve in water to form
d d d d d d d d d d d d d d d
Cu2+ ions
d d
For insoluble copper (II) compounds, react w/ acid acid to form Cu2+
d d d d d d d d d d d
For copper alloys (e.g. brass or bronze), dissolve in conc. nitric acid then neutralise to form
d d d d d d d d d d d d d d d d
Cu2+ d
Cu2+ + I- --> I2 + CuI
d d d d d d d
(overall brown coloured mixture) d d d
Voltaic cell - ANSWER:Converts chemical energy to electrical energy
d d d d d d d d
Made by connecting 2 different half cells, allowing electrons to flow
d d d d d d d d d d
