This I/GCSE Chemistry blogpost will look at an example of how to complete an equation for water of crystallization, let's go!
Heating Hydrated Magnesium Sulfate, MgSO4.XH2O, in a crucible forms anhydrous magnesium sulfate, MgSO4. Use the experimental data below to find the value of x and write the formula of the hydrated salt.
Mass of the empty crucible=42.000g
Mass of the crucible+MgSO4.XH2O=45.210g
Mass of the crucible+MgSO4=43.567g
Step 1-Work out the mass of MgSO4.XH2O and MgSO4 you have
- Mass of MgSO4.XH2O = 45.210-42.000=3.210g
- Mass of MgSO4= 43.567-42.000=1.567
Step 2-Calculate the number of moles of water lost
- Mass of water lost= 3.210-1.567=1.643g
- Number of moles of water lost= Mass/relative atomic mass= 1.643g/ (H2O= 2x1+16)18=0.0913moles
Step 3-Calculate the number of moles of anhydrous salt made
- Molar mass of MgSO4: 24+32+ 94x16) =120g/mol
- Number of moles of MgSO4: mass/relative atomic mass= 1.567/120=0.0131 moles
Step 4-Work out the ratio of moles of anhydrous salt to moles of water
- 0.0131 moles of salt : 0.0913 moles of water
- so 1 moles of salt: 0.0913/0.0131= 6.97 moles of water
Step 5-Round of your result to get a whole number
6.97 moles of water+ 7 moles of water
So the formula of hydrated salt is MgSO4. 7H2O
That is it !
References:
https://www.google.com/url?sa=i&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FMagnesium_sulfate&psig=AOvVaw0KtUiZWF4_B2SW3pShvjmy&ust=1629219041015000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCNDymIWAtvICFQAAAAAdAAAAABAD