Question

A hydrated salt is a solid that includes water molecules within its crystal structure. A student heated a 12.10-gram sample of a hydrated salt to a constant mass of 5.41 grams. What percent by mass of water did the salt contain?

Answer 1

Answer : The percent by mass of water the salt contain is, 55.3 %

Explanation : Given,

Mass of hydrated salt = 12.10 g

Mass of salt = 5.41 g

First we have to calculate the mass of water.

Mass of water = Mass of hydrate salt - Mass of salt

Mass of water = 12.10 g - 5.41 g

Mass of water = 6.69 g

Now we have to calculate the percent by mass of water the salt contain.

$\text{Percent by mass of water}=\frac{\text{Mass of water}}{\text{Mass of hydrate salt}}\times 100$

Now put all the given values in this expression, we get:

$\text{Percent by mass of water}=\frac{6.69g}{12.10g}\times 100$

$\text{Percent by mass of water}=55.3\%$

Therefore, the percent by mass of water the salt contain is, 55.3 %