The hydration number "n" in Sr(NO3)2•nH2O is 4.
<h2>Further Explanation:</h2><h3>Hydrates</h3>
- Hydrates are compounds that contain water of crystallization with a definite mass.
- These compounds are in the form of crystals and can be heated to remove water and form an anhydrous form of the compound.
- Unknown hydrates with an "n" before H2O. For example; Sr(NO3)2•nH2O.
- "n" represents the hydration number or the moles of water of crystalization in hydrates and can be determined using some steps.
<h3>Steps in determining hydration number in hydrates;</h3>
- Determining the mass of water produced when hydrates are heated
- Converting the mass of water to moles
- Convert the mass of anhydrate that is left over to moles.
- Find the mole ratio of anhydrate to water
- Use the mole ratio to write the formula
Therefore:
We can determine the hydration in Sr(NO3)2•nH2O
<h3>Step 1: Mass of water </h3>
Mass of water = Mass of hydrate - mass of anhydrate
= 30.7 g - 22.9 g
= 7.8 g
<h3>Step 2: Moles of water </h3>
Number of moles = mass/ molar mass
= 7.8 g / 18 g/mole
= 0.433 moles
<h3>Step 3; Moles of anhydrate </h3>
Mass of anhydrate = 22.9 g
Number of moles = mass/molar mass
Molar mass of anhydrate Sr(NO3)2 is 211.63 g/mol
Thus;
Number of moles of Sr(NO3)2 = 22.9 g /211.63 g/mol
= 0.108 moles
<h3>Step 4: Mole ratio of anhydrate to water </h3>
Moles of water = 0.433 moles
Moles of anhydrate = 0.108 moles
Mole ratio = 0.108 : 0.433
= 1 : 4
Therefore; The value of n is 4
Hence the formula of the hydrate is Sr(NO3)2• 4H2O
Keywords: Hydrates, water of crystallization, steps in finding the formula of hydrates.
<h3>Learn more about: </h3>
Level : High school
Subject: Chemistry
Topic: Moles
Sub-topic: Formula of hydrates
