AQA CHEMISTRY A-LEVEL COMPREHENSIVE
QUESTIONS AND VERIFIED CORRECT ANSWERS
The ability of an atom to attract the bonding pair of electrons in a covalent bond
Electronegativity
Enthalpy change when 1 mole of a substance is completely burned in oxygen
under standard conditions, all reactants and products being in their standard
states.
Standard Enthalpy of Combustion (R-P) (If you are given combustion data to work out
formation, ISE THE COMBUSTION FORMULA)
Enthalpy change when 1 mole of a compound is formed from its elements under
standard conditions, all reactants and products being in their standard state.
Standard Enthalpy of Formation (P-R) (If you are given formation data to calculate
combustion, USE THE FORMATION EQUATION)
The Enthalpy Change needed to overcome 1 mole of bonds in a gaseous state
averaged over different molecules.
Mean Bond Enthalpy
Average mass of its atoms compared to 1/12th the mass of a carbon-12 atom
Relative Atomic Mass
1. Decreases
2. Shielding is constant
3. Surface charge density is increasing
Atomic radius across a period
1. Increases
2. Shielding increases
3. Lower surface charge density
Atomic radius down a group
Strong electrostatic forces of attraction between cations and the sea of
delocalised electrons flowing through the metallic lattice.
Metallic bonding
the average mass of one molecule of the substance compared to 1/12th of a
carbon-12 atom
Relative molecular mass
Simplest whole number ratio of atoms of each element in a compound
Empirical Formula
The actual number of atoms of each element in a compound
Molecular formula
The amount of energy needed to remove one mole of electrons from one mole of
a gas, to produce one mole of gaseous 1+ ions
First ionisation energy
The amount of energy needed to remove one mole of electrons from one mole of
gaseous, 1+ ions, to produce one mole of gaseous 2+ ions.
Second Ionisation energy
, 1. The mean is an average of the bond enthalpy taken over many different
compounds.
Suggest a reason why the value calculated differs from the mean Xe-F bond enthalpy.
(1)
The enthalpy change for a reaction is independent of its route
Hess' Law
Both the forward and reverse reactions take place simultaneously at the same
rate. The concentration of reactants and products remain constant
Dynamic equilibrium
Same molecular and structural formula, but different spatial arrangement.
Stereoisomers
Different functional groups
Structural Functional Isomer
Functional group on different place of backbone
Structural Positional Isomer
different arrangement of the carbon backbone
Structural Chain Isomer
Change in environment will cause the position of equilibrium to move to oppose
the change
Le Chatelier's Principle
1. Add an aqueous acid to the solution
2. Carbon dioxide gas will be evolved
Test for Carbonate ions (2)
1.Add NaOH
2. Warm gently
3. Red litmus paper turns blue
Test for Ammonium ions (3)
1. Acidity the test solution with HCl,
2. Add solution of BaCl2
3. White precipitate indicates sulphate ions
Test for Sulphate Ions (Group II) (3)
Add nitric acid and silver nitrate - white precipitate (AgCl - soluble in dilute
ammonia)
Test for Chloride ions
Add nitric acid and silver nitrate- cream precipitate (AgBr - Soluble in conc
ammonia)
Test for Bromide ions
Add nitric acid and silver nitrate - yellow precipitate (AgI - Insoluble)
Test for Iodide ions
Add dilute ammonia, AgCl will dissolve, AgBr and AgI will not.
Add conc ammonia. AgBr will dissolve and AgI will not.
Further test for halides
1. Add Tollen's Reagent to the solution.
2. Silver mirror should form. Ketone will observe no reaction
Test for Aldehydes (Tollen's) (2)
QUESTIONS AND VERIFIED CORRECT ANSWERS
The ability of an atom to attract the bonding pair of electrons in a covalent bond
Electronegativity
Enthalpy change when 1 mole of a substance is completely burned in oxygen
under standard conditions, all reactants and products being in their standard
states.
Standard Enthalpy of Combustion (R-P) (If you are given combustion data to work out
formation, ISE THE COMBUSTION FORMULA)
Enthalpy change when 1 mole of a compound is formed from its elements under
standard conditions, all reactants and products being in their standard state.
Standard Enthalpy of Formation (P-R) (If you are given formation data to calculate
combustion, USE THE FORMATION EQUATION)
The Enthalpy Change needed to overcome 1 mole of bonds in a gaseous state
averaged over different molecules.
Mean Bond Enthalpy
Average mass of its atoms compared to 1/12th the mass of a carbon-12 atom
Relative Atomic Mass
1. Decreases
2. Shielding is constant
3. Surface charge density is increasing
Atomic radius across a period
1. Increases
2. Shielding increases
3. Lower surface charge density
Atomic radius down a group
Strong electrostatic forces of attraction between cations and the sea of
delocalised electrons flowing through the metallic lattice.
Metallic bonding
the average mass of one molecule of the substance compared to 1/12th of a
carbon-12 atom
Relative molecular mass
Simplest whole number ratio of atoms of each element in a compound
Empirical Formula
The actual number of atoms of each element in a compound
Molecular formula
The amount of energy needed to remove one mole of electrons from one mole of
a gas, to produce one mole of gaseous 1+ ions
First ionisation energy
The amount of energy needed to remove one mole of electrons from one mole of
gaseous, 1+ ions, to produce one mole of gaseous 2+ ions.
Second Ionisation energy
, 1. The mean is an average of the bond enthalpy taken over many different
compounds.
Suggest a reason why the value calculated differs from the mean Xe-F bond enthalpy.
(1)
The enthalpy change for a reaction is independent of its route
Hess' Law
Both the forward and reverse reactions take place simultaneously at the same
rate. The concentration of reactants and products remain constant
Dynamic equilibrium
Same molecular and structural formula, but different spatial arrangement.
Stereoisomers
Different functional groups
Structural Functional Isomer
Functional group on different place of backbone
Structural Positional Isomer
different arrangement of the carbon backbone
Structural Chain Isomer
Change in environment will cause the position of equilibrium to move to oppose
the change
Le Chatelier's Principle
1. Add an aqueous acid to the solution
2. Carbon dioxide gas will be evolved
Test for Carbonate ions (2)
1.Add NaOH
2. Warm gently
3. Red litmus paper turns blue
Test for Ammonium ions (3)
1. Acidity the test solution with HCl,
2. Add solution of BaCl2
3. White precipitate indicates sulphate ions
Test for Sulphate Ions (Group II) (3)
Add nitric acid and silver nitrate - white precipitate (AgCl - soluble in dilute
ammonia)
Test for Chloride ions
Add nitric acid and silver nitrate- cream precipitate (AgBr - Soluble in conc
ammonia)
Test for Bromide ions
Add nitric acid and silver nitrate - yellow precipitate (AgI - Insoluble)
Test for Iodide ions
Add dilute ammonia, AgCl will dissolve, AgBr and AgI will not.
Add conc ammonia. AgBr will dissolve and AgI will not.
Further test for halides
1. Add Tollen's Reagent to the solution.
2. Silver mirror should form. Ketone will observe no reaction
Test for Aldehydes (Tollen's) (2)
