E x c e l l e n c e i s k e y | 2 0 2 0 2 5 ~ P a g e |1
AS level OCR Chemistry Questions &
100% correct Answers- Latest Test |
Graded A+ | Passed
Isotopes
Ξ -:- Different atomic forms of the same element. Atoms with the same number of
protons but a different number of neutrons
Relative atomic mass
Ξ -:- The mean mass of an atom of an element, compared to 1/12th of the mass of an
atom of carbon-12
Concentration=
Ξ -:- Number of moles ÷ Volume
One mole
Ξ -:- 6.02×10^23
Number of moles=
Ξ -:- mass ÷ molar mass
r.t.p
Ξ -:- 25 ºC
100 kPa (1 atm)
Molar gas volume
Ξ -:- 24 dm³ / mol
One mole of any gas always has the same volume at r.t.p
26/08/2024 | © Copyright- This work may not be copied for profit.
, E x c e l l e n c e i s k e y | 2 0 2 0 2 5 ~ P a g e |2
Number of moles=
Ξ -:- Volume (dm^3) ÷ Molar gas volume (24 dm^3 / mol)
R- Gas constant
Ξ -:- 8.314 J / K / mol
Gas equation
Ξ -:- pV = nRT
(Pa)(m³)(K)
Assumes forces between molecules are negligible and the molecules have a negligible size
Empirical formula
Ξ -:- The smallest whole number ratio of atoms of each element in a compound
Molecular formula
Ξ -:- The actual number of atoms of each element in a compound
Ions:
Nitrate
Carbonate
Sulfate
Hydroxide
Ammonium
Zinc ion
Silver ion
Ξ -:- Formula:
NO3-
CO3²-
SO4²-
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, E x c e l l e n c e i s k e y | 2 0 2 0 2 5 ~ P a g e |3
OH-
NH4+
Zn²+
Ag+
Acids
Ξ -:- Proton donors - produce H+ ions in water
Alkalis
Ξ -:- Proton acceptors - produce OH- ions in water
Acid + Base=
Metal oxide + Acid=
Metal hydroxide + Acid=
Ξ -:- Salt + Water
Metal + Acid=
Ξ -:- Metal salt + Hydrogen
Metal carbonate + Acid=
Ξ -:- Metal salt + Carbon dioxide + Water
Ammonia + Acid=
Ξ -:- Ammonium salt
Methyl orange
Ξ -:- Yellow in alkali, red in acids
Phenolphthalein
26/08/2024 | © Copyright- This work may not be copied for profit.
AS level OCR Chemistry Questions &
100% correct Answers- Latest Test |
Graded A+ | Passed
Isotopes
Ξ -:- Different atomic forms of the same element. Atoms with the same number of
protons but a different number of neutrons
Relative atomic mass
Ξ -:- The mean mass of an atom of an element, compared to 1/12th of the mass of an
atom of carbon-12
Concentration=
Ξ -:- Number of moles ÷ Volume
One mole
Ξ -:- 6.02×10^23
Number of moles=
Ξ -:- mass ÷ molar mass
r.t.p
Ξ -:- 25 ºC
100 kPa (1 atm)
Molar gas volume
Ξ -:- 24 dm³ / mol
One mole of any gas always has the same volume at r.t.p
26/08/2024 | © Copyright- This work may not be copied for profit.
, E x c e l l e n c e i s k e y | 2 0 2 0 2 5 ~ P a g e |2
Number of moles=
Ξ -:- Volume (dm^3) ÷ Molar gas volume (24 dm^3 / mol)
R- Gas constant
Ξ -:- 8.314 J / K / mol
Gas equation
Ξ -:- pV = nRT
(Pa)(m³)(K)
Assumes forces between molecules are negligible and the molecules have a negligible size
Empirical formula
Ξ -:- The smallest whole number ratio of atoms of each element in a compound
Molecular formula
Ξ -:- The actual number of atoms of each element in a compound
Ions:
Nitrate
Carbonate
Sulfate
Hydroxide
Ammonium
Zinc ion
Silver ion
Ξ -:- Formula:
NO3-
CO3²-
SO4²-
26/08/2024 | © Copyright- This work may not be copied for profit.
, E x c e l l e n c e i s k e y | 2 0 2 0 2 5 ~ P a g e |3
OH-
NH4+
Zn²+
Ag+
Acids
Ξ -:- Proton donors - produce H+ ions in water
Alkalis
Ξ -:- Proton acceptors - produce OH- ions in water
Acid + Base=
Metal oxide + Acid=
Metal hydroxide + Acid=
Ξ -:- Salt + Water
Metal + Acid=
Ξ -:- Metal salt + Hydrogen
Metal carbonate + Acid=
Ξ -:- Metal salt + Carbon dioxide + Water
Ammonia + Acid=
Ξ -:- Ammonium salt
Methyl orange
Ξ -:- Yellow in alkali, red in acids
Phenolphthalein
26/08/2024 | © Copyright- This work may not be copied for profit.
