Lab 1 - Determining Hydrate Formulas

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Raghav Ramabadran                                                                15 October 2007


Grade 11 IB Chemistry

Mr. Laratt Smith

Lab 1: Determining the Water of Crystallisations


The purpose of this lab is to determine the number of moles of water of crystallisations in crystals of a white hydrated salt which is called Zinc (II) Sulfate (ZnSO4) by heating it to constant mass in a crucible. Also this lab will determine the formula and the name for the hydrated salt.


  • A small crucible with lid
  • A pipe clay triangle
  • A Bunsen burner
  • A tool that emits flames (a lighter for example)
  • A Scupula, tong, and the retort stand
  • A weighing machine that shows the mass in grams (g)
  • A pair of goggles
  • A cookie sheet


  1. Wear your goggles, and weigh the empty crucible with its lid on the weighing machine, and record the results as accurately as possible.
  2. Take the scupula and fill the crucible one-third (1/3rd) full of the Zinc (II) Sulfate (ZnSO4) crystals. Replace the lid and reweigh the crucible, and record the results.
  3. Place the crucible with the lid on the retort stand. Heat the crucible with the lid strongly on a pipe clay triangle for about ten minutes, and then with the tongs take the crucible and place it on the cookie sheet to cool for a few minutes.
  4. When it is cool enough to be held in your hand, reweigh the crucible with the lid, and record the results.
  5. Repeat steps 3-4 until you have you results for at least the mass of the crucible with lid, and salt after the fourth heating.

Data Chart (Instrumental, Procedural, and Percent Uncertainty included):

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Determining the Number of moles of Water of Crystallisation and Hydrate formula of Zinc (II) Sulfate (ZnSO4): 


In conclusion, to find out the hydrate formula of any salt, the salt has to be heated until there is no further weight loss. This is so because when determining the hydrate formula, you have to find the total mass of the hydrated salt in the crucible with the lid, the total mass of the salt in the ...

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