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Design an experiment to accurately determine the empirical formula of a given hydrate. Predict how experimental factors will impact the accuracy and precision of results. Calculate the molar ratio of water to anhydrous solid to determine the hydrate's formula.
- 1.7: Experiment 6 - Hydration of Salt - Chemistry LibreTexts
Design an experiment to accurately determine the empirical...
- 3: Experiment 3 - Hydrated Salt - Chemistry LibreTexts
In order to determine the formula of the hydrate,...
- 1.7: Experiment 6 - Hydration of Salt - Chemistry LibreTexts
Design an experiment to accurately determine the empirical formula of a given hydrate. Predict how experimental factors will impact the accuracy and precision of results. Calculate the molar ratio of water to anhydrous solid to determine the hydrate's formula.
Example #1: A 15.67 g sample of a hydrate of magnesium carbonate was heated, without decomposing the carbonate, to drive off the water. The mass was reduced to 7.58 g. What is the formula of the hydrate? Solution: 1) Determine mass of water driven off: 15.67 − 7.58 = 8.09 g of water. 2) Determine moles of MgCO 3 and water:
The formula of a hydrate consists of the formula of the anhydrous (without water) compound followed by a dot, then the number of molecules of water that crystallize with one formula unit of the compound, then the formula of water.
In this experiment a hydrated salt will be heated to constant weight, removing the water of hydration. The loss of weight will be the weight of water present in the original salt.
A common example is anhydrous cobalt(II) chloride, CoCl2 (blue in color). When in contact with moisture, this substance absorbs water to create cobalt(II) chloride hexahydrate, CoCl2.6H2O (pink in color). In this experiment, hydrated salts will be heated.
In order to determine the formula of the hydrate, [\(\text{Anhydrous Solid}\ce{*}x\ce{H2O}\)], the number of moles of water per mole of anhydrous solid (\(x\)) will be calculated by dividing the number of moles of water by the number of moles of the anhydrous solid (Equation \ref{6}).
