calculations Flashcards
1
Q
what is relative atomic mass (Ar)?
A
the mass of an atom measured on the scale by comparing it to the mass of other atoms
2
Q
where can the relative atomic mass be found?
A
the top number
3
Q
what is relative molecular mass (Mr)?
A
the mass of a molecule of a substance
4
Q
how do you calculate the percentage composition?
A
Mr
5
Q
how do you calculate the empiracle/ simplest formula?
A
1 - write the symbols
2 - write mass/% from question
3 - find the Ar
4 - divide the mass by the Ar
5 - divide each of these answers by the smallest of the two answers
6 - use these numbers to write the formula
6
Q
how do you calculate moles?
A
Ar
7
Q
how do you calculate mass?
A
moles X Ar
8
Q
how do you calculate the mass made in an experiment?
A
1 - balance the equation 2 - work out the Mr 3 - calculate moles 4 - find molar ratio 5 - calculate mass
9
Q
how do you calculate percentage yield?
A
theoretical mass
