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Hydrated Compounds. … plus a quick review of mass data…. Quick Revies.
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Hydrated Compounds … plus a quick review of mass data…
Quick Revies • Sulfur Trioxide is made industrially in enormous quantities by combining oxygen and sulfur dioxide. What amount (moles) of sulfur trioxide is represented by 1.00kg of sulfur trioxide? How many molecules? How many sulfur atoms? How many oxygen atoms?
Quick Review • In 2006, a Russian team discovered an interesting molecule they called “sulflower” because of its shape and because it was based on sulfur. It is composed of 57.17% S and 42.83% C and has a molar mass of 448.70 g/mol. Determine the empirical and molecular formulas of “sulflower”.
Quick Review • We can find empirical and molecular formulas from percent composition… but what about from mass data? • Let’s give that a try
Formula of a Compound from Combining Masses • Gallium oxide, GaxOy, forms when gallium is combined with oxygen. Suppose you allow 1.25g of gallium (Ga) to react with oxygen and obtain 1.68g of GaxOy. What is the formula of the product?
Formula of a Compound from Combining Masses • Remember the steps from before: • Percent to mass • Mass to mole • Mole ratios • Multiply til whole
Formula of a Compound from Combining Masses • What’s the chemical reaction for this example? • Do we need it? • Let’s set it up • Gallium + Oxygen GaxOy 1.25g ? 1.68g
Formula of a Compound from Combining Masses • Ga – 1.25g • O – (1.68g - 1.25g) = 0.43g • Convert to moles: 1.25g Ga x 1 mol/69.72 g = 0.0179 mol Ga 0.43g Ga x 1 mol/16.0 g = 0.027 mol O • Mole Ratio Mole Ratio 0.27 mol O/0.0179mol Ga = 1.5 Ga2O3
Hydrated Compounds • Compounds in which molecules of water are associated with ions of the compound (notice- associated with, not bonded with) • Happens when some ionic compounds are prepared in water solutions and then isolated as solids, sometimes water molecules get trapped in the lattice structure
Hydrated Compounds • Example : CuCl2 ● 2H2O • If this compound were to lose the water (say, it is heated), we then say that it is in the anhydrous form