4.4.1 - relative formula mass

Question 1

how is RFM calculated

Answer 1

by adding the relative atomic masses of the atoms or ions

Question 2

e.g. calculate RFM of H2O

Answer 2

(2x1) + (16x1) = 18

Question 3

what does percentage by mass show?

Answer 3

the mass of a substance that comes from a particular element

Question 4

percentage by mass equation:

Answer 4

%y = (mass of y/RFM) x 100

Question 5

e.g. find the percentage of C in C3H8

Answer 5

%C = (C3/C3H8) x 100
= [(3x12)/(3x12)+8]
= 81.8%