Calculate the formula weight of each of the following to three significant figures, using a table of atomic weight (AW): (a) chloroform `CHCl_3 (b) ` Iron (III) sulfate , `Fe_2(SO_4)_3`.

Explanation

a. ` 1 xx AW` or C = 12.0 amu
`1 xx AW ` of H = 1.0 amu
` 3 xx AW` of Cl `=3 xx 35.45`= `ul(106.4 " amu")`
Formula weight of `CHCl_3`= `ul(119.4 " amu ")`
The ansser rounded to three significant figure is 119 amu.
b. Iron (III) Sulfate
` 2 xx `Atomic weight of Fe `=2 xx 55.8`=111.6 am
` 3 xx ` Atomic weight of O `= 12 xx 16 = ul(192.0 " amu ")`
The answer rounded to three significant figure is ` 4.00 xx 10^(2) ` amu.