7 CHEMICAL CALCULATIONS (mol)

Question 1

how to calculate relative atomic mass (Ar)

Answer 1

js take it from the periodic table
[(% x mass) of each isotope added up]

Question 2

how to calculate relative molecular mass (Mr)

Answer 2

all the Ar added up
O = 16.0 –> Ar
O3 = 16.0x3=48 –>Mr

Question 3

how to calculate percentage composition of a compound

Answer 3

Ar of the element / Mr of the compound
% of H in H2O
H=1x2
O=16.0
2/16+2 = 1/9

Question 4

calculate percentage composition of water in a compound

Answer 4

its the same as b4 js tat now H2O is considered 1 element
5(H2O) = 5 x 18
5(O) = 5 x 16

Question 5

how much is one mole

Answer 5

6.02 x 10^23

Question 6

relationship between
mass(g), number of moles(mol), molar mass(Ar,Mr)

Answer 6

its the same as the dst triangle
mass(g) on top
moles (mol) molar mass (Ar.Mr)

Question 7

what is the empirical formula for

Answer 7

the empirical formula of a compound is the simplest formula which shows the ratio of the atoms of the different elements in the compounds.

Question 8

formula for empirical formula

Answer 8

1. mass(g) of each element (given in qn)
2. molar mass(Ar,Mr) of element (given in period table)
3. no. of moles(mol) DST it g/Mr
   4.Mole ratio (divide each value by the smallest value) from 3.
4. simple ratigo it