Weak acid - Only a small proportion of acid molecules dissociate

A – LEVEL CHEMISTRY PAPER 1
QUESTIONS AND ANSWERS
2ND EDITION 2025




Weak acid - ✔✔✔Only a small proportion of acid molecules dissociate


Strong acid - ✔✔✔An acid that fully dissociates


2nd Ionisation enthalpy - ✔✔✔Enthalpy change when one mole of gaseous 1+ ions loses one
electron per ion to form one mole of gaseous 2+ ions


1st electron affinity - ✔✔✔Enthalpy change when one mole of gaseous atoms gains one
electron per atom to form one mole of gaseous 1- ions



pg. 1

, 2nd electron affinity - ✔✔✔Enthalpy change when one mole of gaseous 1- ions gains one
electron per ion to form one mole of gaseous 2- ions


Enthalpy of atomisation - ✔✔✔Enthalpy change when one mole of gaseous atoms is produced
from an element in its standard state


Chelate - ✔✔✔Name given to the complex formed when a metal ion is surrounded by
polydentate ligands
Which are the basic oxides in period 3? - ✔✔✔NaOH/MgO/Al2O3 (amphoteric)


Which are the acidic oxides in period 3? - ✔✔✔Al2O3 (amphoteric) /SiO2/P4O10/SO2/SO3


Equation to show acidic nature of Al2O3 - ✔✔✔Al2O3 + 2NaOH + 3H2O -> 2NaAl(OH)4


Equation to show basic nature of Al2O3 - ✔✔✔Al2O3 + 6HCl -> 2AlCl3 + 3H2O


What ion does SO2 form after reacting with base - ✔✔✔SO32-


What ion does P4O10 form after reacting with base - ✔✔✔PO43-


What ion does Al2O3 form after reacting with base and water - ✔✔✔Al(OH)4-


Equations for hydrogen fuel cell in acidic conditions - ✔✔✔H2 -> 2H+ + 2e-
O2 + 4H+ + 4e- -> 2H2O


Equations for hydrogen fuel cell in alkaline conditions - ✔✔✔H2 + 2OH- -> 2H2O + 2e-


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