CHEMLAB HYDRATE FORMULA SERIES

Save the residue and perform your calculations.Weigh and record the mass of the cooled crucible with its cover and content (anhydrous residue). Center the crucible’s cover and let it cool down to room temperature.Heat the content of the crucible with its cover slightly open to allow the water of hydration to escape, first gently (about 10 minutes), then strongly (about 5 minutes). Record the mass of the crucible, cover and sample. Making sure to handle the crucible and its cover with clean tongs, add about 1 g (weighed to the nearest 0.001 g) of the unknown hydrate.Weigh the crucible with its cover to the nearest 0.001 g. Allow the crucible to cool down to room temperature (do not set the hot crucible on the bench top). Set the crucible with its cover slightly open on a clay triangle and heat strongly for at least 10 minutes.Rinse the crucible and its cover with distilled water. Pour the used nitric acid in the waste container provided. Using crucible tongs, clean a porcelain crucible and its cover using concentrated nitric acid (6 M).water molecules incorporated into crystal in a definite proportion. In this section we will determine the number of moles of water present per mole of anhydrous solid in a given hydrate. ordered packing of cations and anions in an inorganic crystal. Part D: Determination of the formula of a hydrate If the compound possesses all three of the above-mentioned properties, it is a true hydrate if at least one of them is not present, the compound is not.Ĭompounds to be tested: Nickel (II) chloride, Cobalt (II) chloride, Sucrose, Calcium Carbonate, Barium chloride, Sodium tetraborate, Potassium chloride. Let the residue cool down (put the test tube in a beaker not on a plastic test tube rack) then try to dissolve in about 3 mL of water (about 1/3 of the small test tube), warming gently if necessary to dissolve the residue (dissolve only substances that have shown condensation).Heat the test tube and note any condensation that may appear at the mouth of the test tube as evidence of dehydration, note the color of the residue.For each of the chemical compounds below, place a pea-sized (≈30 mg) amount of the compound (just enough to cover the bottom of the test tube) in a dry test tube and note its color.The calculations in the lab book are convoluted, and.

For a compound to be a true hydrate, it has to show all properties of true hydrates, including evolution of water upon heating, solubility of its anhydrous residue in water and reversibility in the color of the residue back to the color of the hydrate when dissolved in water. If you know the molar ratio of the formula units to water, then you will have the hydrate formula.

Some compounds may possess some of the properties of hydrates without being true hydrates.

CHEMLAB HYDRATE FORMULA SERIES

In this section you will try to determine through the testing of a series of compounds, which ones are true hydrates. To determine the formula of a hydrate experimentally, we must calculate the mole: mole ratio of the water portion compared to the anhydrate portion.

Chemlab hydrate formula