OCR A LEVEL CHEMISTRY MODULE 2 Exam Questions With
Detailed Answers
Define atom economy
The percentage of atoms that react to form the desired product
What is water of crystallisation?
Water molecules that are bonded into a crystalline structure of a compound
What is the equation for atom economy?
(total Mr of desired products/ total Mr of all products) x 100
Why is a high atom economy important?
More efficient reactions, preserves raw materials, reduces waste
Name a group of weak acids
Carboxylic acids
Name strong acids
HCl, HNO3, H2SO4
Define acid
A proton donor that is able to neutralise a base; contains H+ ions
What is the difference between a strong acid and a weak acid?
A strong acid fully dissociates in water whereas a weak acid only partially
dissociates in water
What is the formula of ethanoic acid?
CH3COOH
What is a salt?
Compound formed when the H+ ion in an acid is replaced by a metal ion
Define neutralisation
A chemical reaction in which an acid and a base react together to produce a salt
and water
What is an alkali?
, A soluble base that releases OH- ions when dissolved in water
What are polyprotic acids?
Acids that donate more than one proton
Name a monoprotic acid
HNO3
Name a diprotic acid
H2SO4
Name a triprotic acid
H3PO4
Acid + metal
Salt + hydrogen
Acid + metal oxide
Salt + water
Acid + alkali
Salt + water
Acid + metal carbonate
Salt + water + carbon dioxide
Why is ammonia alkali?
Doesn't produce OH- directly: it reacts with water first and accepts a proton to
produce ammonium ions and OH- ions
Define isotope
Atoms of the same element with the same number of protons but different
number of neutrons
Define relative isotopic mass
The mass of an isotope relative to 1/12th of the mass of an atom of carbon-12
Define relative atomic mass
The weighted mean mass of an atom relative to 1/12 of the mass of a Carbon-12
atom
What is the relative mass of an electron?
Detailed Answers
Define atom economy
The percentage of atoms that react to form the desired product
What is water of crystallisation?
Water molecules that are bonded into a crystalline structure of a compound
What is the equation for atom economy?
(total Mr of desired products/ total Mr of all products) x 100
Why is a high atom economy important?
More efficient reactions, preserves raw materials, reduces waste
Name a group of weak acids
Carboxylic acids
Name strong acids
HCl, HNO3, H2SO4
Define acid
A proton donor that is able to neutralise a base; contains H+ ions
What is the difference between a strong acid and a weak acid?
A strong acid fully dissociates in water whereas a weak acid only partially
dissociates in water
What is the formula of ethanoic acid?
CH3COOH
What is a salt?
Compound formed when the H+ ion in an acid is replaced by a metal ion
Define neutralisation
A chemical reaction in which an acid and a base react together to produce a salt
and water
What is an alkali?
, A soluble base that releases OH- ions when dissolved in water
What are polyprotic acids?
Acids that donate more than one proton
Name a monoprotic acid
HNO3
Name a diprotic acid
H2SO4
Name a triprotic acid
H3PO4
Acid + metal
Salt + hydrogen
Acid + metal oxide
Salt + water
Acid + alkali
Salt + water
Acid + metal carbonate
Salt + water + carbon dioxide
Why is ammonia alkali?
Doesn't produce OH- directly: it reacts with water first and accepts a proton to
produce ammonium ions and OH- ions
Define isotope
Atoms of the same element with the same number of protons but different
number of neutrons
Define relative isotopic mass
The mass of an isotope relative to 1/12th of the mass of an atom of carbon-12
Define relative atomic mass
The weighted mean mass of an atom relative to 1/12 of the mass of a Carbon-12
atom
What is the relative mass of an electron?
