These are detailed Revision Notes for Topic Three (Quantitative Chemistry) of AQA GCSE Chemistry. They are written by me, using a combination of class notes, text books and revision guides. I have also uploaded the other chapters in my store.
Quantitative Chemistry
Relative Formula Mass and Chemical Reactions:
• Something’s relative formula mass (Mᵣ) is the sum of the relative atomic mass of the atoms in the
formula.
• In any chemical reaction, the total mass of all the products must equal the total mass of all the reactants.
Atoms cannot be destroyed or created in a chemical reaction.
Equations and Conservation of Mass:
• 2Mg + 0₂ à 2MgO
0.23g 0.33g – Mass appears to rise because the O₂ that reacted wasn’t weighed as the gas but
was as part of MgO.
• CuCO₃ à CO₂ + Cu0
1g 0.7g – Mass appears to decrease because the CO₂ released as a product wasn’t weighed.
The Mole:
• Each element has a different number of protons and neutrons in its nucleus. Because of this each
element will have a different mass.
• However, these masses are very small and awkward to deal with. So instead of dealing with their actual
mass we use their relative atomic mass. (Aᵣ).
• Relative atomic mass is defined as:
o The weighted average mass of an atom relative to 1/12th the mass of carbon-12 which has a
mass of exactly 12.
• Because the mass of a single atom is so tiny it is very hard to deal with. Instead we use the number of
atoms in 1 relative atomic mass of the atom in grams.
E.g. the number of atoms:
o 1g of H atoms (Aᵣ=1)
o 12g of C atoms (Aᵣ=12)
• This number of atoms is called Avogadro’s constant or number.
• There are 6.02x10²³ atoms in 1 relative atomic mass of an atom. Mass
• If we have 6.02x10²³ particles, then we have 1 mole of them.
• The abbreviation for the mole is ‘mol’.
• The mass of 1 mole of an atom is the relative atomic mass (Aᵣ) of the
atom.
Aᵣ or
Mol
• The mass of 1 mole of a compound is the relative atomic mass (Mᵣ) of Mᵣ
the compound.
Moles and Chemical Equations:
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller emilysarahjudge. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $3.86. You're not tied to anything after your purchase.
