RELATIVE ATOMIC MASS: Given by the symbol Ar
s- Calculated from the Mass Number and Relative Abundances of All the Isotopes of a particular Element
Example for Isotopes:
s
The Table Shows Information about the Isotopes in a sample of Rubidium
Use Information from the Table to Calculate the Relative Atomic Mass of
this Sample of Rubidium. Give your Answer to One Decimal Place
( 72 x 85 ) + ( 28 x 87 )
____________________________ = 85.6
100
Relative Atomic Mass = 85.6
|
s
RELATIVE FORMULA MASS: Given by the Symbol Mr
s- To calculate the Mr of a substance, you have to add up the Relative Atomic Masses of all the Atoms present in the formula
Example:
s
SUBSTANCE
|
ATOMS PRESENT
|
Mr
| |
HYDROGEN
( H2 )
|
2 x H
|
( 2 x 1 ) = 2
| |
WATER ( H2O )
|
( 2 x H ) + ( 1 x O )
|
( 2 x 1 ) + 16 = 18
| |
POTASSIUM CARBONATE
( K2CO3 )
|
( 2 x K ) + ( 1 x C ) + ( 3 x O )
|
( 2 x 39 ) + 12 + ( 3 x 16 ) = 138
| |
CALCIUM HYDROXIDE
( Ca(OH)2 )
|
( 1 x Ca ) + ( 2 x O ) + ( 2 x H )
|
40 + ( 2 x 16 ) + ( 2 x 1 ) = 74
| |
AMMONIUM SULFATE
( (NH4)2SO4 )
|
( 2 x N ) + ( 8 x H ) + ( 1 x S ) + ( 4 x O )
|
( 2 x 14 ) + ( 8 x 1 ) + 32 +
( 4 x 16 ) = 132
|
No comments:
Post a Comment