4.4 - Moles I Flashcards
1
Q
calculate relative formula masses from relative atomic masses
A
Mr = sum of relative atomic masses
2
Q
unit for amount of substance
A
mole (mol)
3
Q
moles
A
mass / RFM
4
Q
mass
A
moles x RFM
5
Q
unit for relative formula mass
A
g mol -1
6
Q
percentage yield
A
amount product produced / maximum amount of product possible x100
7
Q
experiment to find formula of magnesium oxide
A
- weigh pure magnesium
- heat in crucible to form magnesium oxide (reacts w/ air)
- weigh mass of magnesium oxide
oxygen mass = mass MgO - mass Mg
calculate ratio of mol Mg to mol O
- form empirical formula
8
Q
molecular formula
A
number of atoms of each element in a compound
9
Q
empirical formula
A
simplest whole number ratio of elements
10
Q
molecular formula calculation
A
- find elements RFM
- Mr/RFM
- answer x empirical formula
