Question

A 25.0 gram sample of a hydrate of iron(III) phosphate was heated until no more water was driven off. The mass of the anhydrous salt is 16.9 grams. What is the % water in the hydrate?

Answer 1

32.4%

Step-by-step explanation:

Given parameters:

Mass of hydrated sample = 25g

Mass of anhydrous salt = 16.9g

Unknown:

Percentage of water in the hydrate = ?

Solution:

Obviously, there is a mass difference between the original hydrated sample and anhydrous salt which should indicate clearly that the mass loss is due to the evaporated water from the salt.

Mass of salt of water = mass of hydrated salt - mass of anhydrous salt

= 25g - 16.9g

= 8.1g

Percentage of water =
`(mass of water)/(mass of hydrate) x 100`

=
`(8.1)/(25) x 100`

= 32.4%