Amount of Substance Flashcards
What is molecular formula?
Actual number of atoms of each element in a compound
What is empirical formula?
simplest whole number ratio of atoms of each element in a compound
What is the formula for atom economy
(mr of desired products/ mr of all reactants) x 100
what is the calculation for NUMBER of moles
number of molecules/ avogadro
What is %yield?
Tells us about the practical efficiency of the process
What is the formula for % yield?
(actual yield/mass/ theoretical mass) x 100
What is the formula for actual yield?
(percentage yield x theoretical yield) / 100
What is the equation for %purity?
(actual mass/impure mass) x 100
what is the formula for apparatus error?
(margin of error/quantity) x100
what is the ideal gas equation?
pv = nRt
How do you work out empirical formula
- divide the percentage of the element by its Mr
- Work out the ratio of all elements by dividing by the smallest number
- Ratio should be whole numbers
How do you calculate molecular formula
divide the relative formula mass of the molecular structure the relative formula mass of the empirical structure
how can you calculate the limiting/excess reactant?
- work out the moles of both reactants
- reactant with the smallest value is limiting
how do you calculate the average titre
titres (volume) within 0.1 of eachother
subtract them then divide by 2
what is a back titration?
A base is treated with an excess of acid on the leftover acid is titrated (vice versa)
You can then work back to find the original base that reacted
How can you use the limiting reagent to work out the maximum mass of products that can be made?
- after working out the limiting use the ratio to calculate moles of the product
- use moles to calculate mass
define atomic number
number of protons in an atom
