Physical Chemistry questions &
Answers 100% Correct!!
Why might the emf of a cell be less than the standard electrode potential? - ANSWER Because
concentration of Cu2+ is less than 1 mol dm-3 / less than standard
equilibrium moves to left
What is ammonia oxidised to? - ANSWER nitrogen
Predict what you would see when aqueous sodium ferrate(VI) is added to aqueous potassium iodide
- ANSWER iodine so a brown (solution) formed
Fe3+ formed which is yellow or orange
Fe2+ formed which is green
Describe a test to show the presence of iron(III) ions in a solution of FeSO4.7H2O. - ANSWER Add
aqueous sodium hydroxide which will give a brown/rusty ppt
Why would you remove excess copper before titrating iron with potassium manganate? - ANSWER
Copper may react with potassium manganate(VII)
iron(III) ions formed in titration may be reduced back to iron(II) ions by the copper
Explain why the H—O—H bond angle in the water ligand is 107° rather than 104.5°. - ANSWER
Water molecule has 2 lone pairs and 2 bonding pairs
Water ligand has 1 lone pair and 3 bonding pairs
Lone pairs repel more than bonding pairs
What is a complex ion? - ANSWER Central ion surrounded by ligands
An electron pair acceptor
What is a ligand? - ANSWER Molecule/ion with a lone pair of electrons
Able to form a dative covalent bond
Answers 100% Correct!!
Why might the emf of a cell be less than the standard electrode potential? - ANSWER Because
concentration of Cu2+ is less than 1 mol dm-3 / less than standard
equilibrium moves to left
What is ammonia oxidised to? - ANSWER nitrogen
Predict what you would see when aqueous sodium ferrate(VI) is added to aqueous potassium iodide
- ANSWER iodine so a brown (solution) formed
Fe3+ formed which is yellow or orange
Fe2+ formed which is green
Describe a test to show the presence of iron(III) ions in a solution of FeSO4.7H2O. - ANSWER Add
aqueous sodium hydroxide which will give a brown/rusty ppt
Why would you remove excess copper before titrating iron with potassium manganate? - ANSWER
Copper may react with potassium manganate(VII)
iron(III) ions formed in titration may be reduced back to iron(II) ions by the copper
Explain why the H—O—H bond angle in the water ligand is 107° rather than 104.5°. - ANSWER
Water molecule has 2 lone pairs and 2 bonding pairs
Water ligand has 1 lone pair and 3 bonding pairs
Lone pairs repel more than bonding pairs
What is a complex ion? - ANSWER Central ion surrounded by ligands
An electron pair acceptor
What is a ligand? - ANSWER Molecule/ion with a lone pair of electrons
Able to form a dative covalent bond
