C3.1 - Chemical Reaction Stoichiometry Flashcards
RAM - Ar
RAM = top number, number of protons + neutrons
RFM - Mr
Relative formula mass
The “RAM’S” of a compound added
Atomic number
The number of protons in the nucleus of an atom
What are moles measured in?
Avogadros constants
What is Avogadro’s constant?
6.022 X 10²³
The number of particles in one mole
- One mole of carbon = …
2. One mole of oxygen = …
- 12g as carbons RAM = 12
2. 16g as oxygens RAM = 16
RAM of helium
4
Diatomic molecules
Molecules composed of only 2 atoms - of the same or different chemical elements.
Mass of
- One mole of oxygen atoms
- One mole of oxygen gas
- 16g
2. 32g - as oxygen gas is O2
Moles equation
Mass (g) = moles (n) x RAM or RFM
Stoicheometry
AKA molar ratios
Refers to mole relationships between atoms/compounds/ions
Reacting masses
- Balance equation
- Convert mass to moles
- Find molar ratio of know:unknown
- Use molar ratio to find moles of unknown
- Convert moles to grams
what is a limiting reactant?
the substance in a chemical reaction that:
- is used up first
- stops the reaction
- limits the amount of product that can form
percentage yield formula
percentage yield = (actual yield/ theoretical) x 100
why might a reaction not give 100% percentage yield?
- reaction may have other products - makes not only the desired product
- reaction may b reversible + not all reactants make product
- some product may be lost when purifying (filtering / transferring between containers)
