C4 - chemical calculations Flashcards
What are Ar and Mr
Ar is the atomic mass of an atom (protons+neutrons)
Mr is the relative molecular mass (all of the Ar’s for a molecule added up)
Moles formula
Mass = Mr/moles
What are moles
A measure of amount of molecules in a substance (1 mole is the number of carbon 12 atoms in 1 gram)
What is thermal decomposition
Breaking down a substance to smaller molecules by heating
Formula for percentage yield
Percentage yield = mass of product / total mass
What is the limiting reactant
The substance not in excess that limits are reaction because there isn’t enough of it
What two ways are there to measure concentration
Moles / dm^3 or g / dm^3
2 formulas for concentration
Concentration = mass / volume
Concentration = moles / volume
What is a standard solution
A solution of known concentration, mass and volume (used in titrations to find quantities of other solutions) made of a primary standard
What is a primary standard
A compound which is stable, high purity and soluble in water
What volume is one mole of gas
24dm^3 at 20 degrees and atmospheric pressure
What is the difference between percentage yield and atom economy
Percentage yield uses moles, atom economy uses mass
