# Calculate the

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"Calculate the"

```					Hydrates

Purpose: To determine the empirical formula for a hydrate.

Procedure:
1. Pour two scoopula fulls of the assigned hydrate into a pestle. Grind hydrate with
mortar to powderize.
2. Mass out between 2 – 3 grams of hydrate. Record the mass of the hydrate.
3. Pour the hydrate into a clean, dry test tube.
4. Heat the hydrate in a hot Bunsen burner flame as directed. Continue heating until all
steam and condensation have been removed from test tube.
5. Cool the test tube for a minute and then mass the test tube and contents (anhydride).
6. Repeat heating and massing until a consistent mass is reached.

Data Table:
Mass of empty test tube (g)
Mass of test tube with hydrate (g)
Mass of test tube with anhydride (g) #1
Mass of test tube with anhydride (g) #2
Mass of test tube with anhydride (g) #3

Calculations:
1. Determine the mass of the hydrate.
2. Determine the mass of the anhydride.
3. Determine the mass of the water removed.
4. Determine the formula of the hydrate.

Questions:
1. What is the correct formula for your hydrate? See your instructor for this information.
2. Calculate the % composition of water in your hydrate using the correct formula.
3. Calculate the mass of water that should have been removed from your sample. This is
the theoretical or accepted value.
4. Calculate the % error using the mass of the water removed in your sample as the
experimental value.
5. How would the chemical formula of the hydrate change if some of your sample had
fallen out of the test tube while you were heating it in the Bunsen burner? (Prove this by
describing how calculated values of mass of water would change.)

Conclusion:
What was your experimental chemical formula for your hydrate? What was the correct
formula? What was the % error for mass of water that should have been removed from