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Lab Activity - Composition of Hydrates !

25 March, 2014 !

Edwin Leech !

Joelle Reitz !

I. Purpose The purpose of this lab was to show how ionic compounds called hydrates go from having water to being an anhydrous salt (salt without water). It was also to show physical changes during the transition from hydrate to anhydrous salt, like colour or texture. !II. Procedure After all the lab equipment was collected, the evaporating dish was placed above the bunsen burner. It was heated for three minutes to make sure that there wasnt any left over water that needed to be evaporated. After it had cooled down, the mass of the dish was recorded and approximately 2.00 grams of one of the hydrates was added to the dish. The dish was placed above the burner again and gently heated for 3-4 minutes, noting any changes in appearance after the time was up. It was then heated again for around 5-6 minutes on a higher heat, again noting the changes in appearance. After the dish had cooled, the mass of the evaporating dish and the anhydrous salt was measured and recorded. All these steps were repeated for the second hydrate. !III. Materials

CuSO4 x H20 MgSO4 x H20 !

IV. Equipment Safety goggles Lab apron Evaporating dish Crucible tongs Microspatula Ring stand Iron ring Wire gauze Digital Mass balance Bunsen burner !

V. Data

Evaporating dish: Mass #1: 44.47g Mass #2: 44.43g !

Mass of Hydrate (g)

Mass of anhydrous salt (g)

Appearance at 4 mins.

Appearance at 10 mins.

CuSO 2.02 0.78 most is light blue, intense blue in centre, more

powdery than before

very pale green-blue, clumpy, almost light

grey

MgSO 2.06 1.02 white, clumpy, powdery

white, more clumpy, more powdery than

before

VI. Calculations Mass of water lost: mass of Hydrate - mass of Anhydrous Salt 1) 2.02g - 0.78g = 1.24g 2) 2.06g - 1.02g = 1.04g Percentage of water in Hydrate: [(mass of water lost)/(mass of Hydrate)] 100 1) (1.24g / 2.02g) 100 = 61.4% 2) (1.04g / 2.06g) 100 = 50.5% Percentage of salt in Hydrate: [(mass of anhydrous salt)/(mass of Hydrate)] 100 1) (0.78g / 2.02g) 100 = 38.6% 2) (1.02g / 2.06g) 100 = 49.5% !VII. Questions 1. Name each of the following hydrate compounds: a) LiNO3 3H20 Lithium Nitrate Trihydrate b) MgSO3 6H20 Magnesium Sulfite Hexahydrate c) BaI2 2H20 Barium Iodide Dihydrate 2. Write correct formulas for the following hydrate compounds a) Iron (III) Nitrate Hexahydrate Fe(NO3)3 6H20 b) Calcium Chloride Dihydrate CaCl2 2H20 c) Barium Hydroxide Octahydrate Ba(OH)2 8H20 !VIII. Conclusions When a compound goes from being a hydrate to being an anhydrous salt, physical changes take effect too. This process is done by heating up the hydrate, causing the water to evaporate, which makes the anhydrous salt look dry and powdery and can cause it to clump. By subtracting the mass of the salt from the hydrate, you can find the mass of the water lost. With this, you can also find the percentage of water in the hydrate, along with the percentage of salt in the hydrate.