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1. Refer to the periodic table and predict the empirical formula for each of the

ID: 856411 • Letter: 1

Question

1. Refer to the periodic table and predict the empirical formula for each of the following oxides given the formula of aluminum oxide, Al2O3 (a) B?O? ______ (b) Ga?O? _______ (c) In?O?_________ (d) Tl?O? _______ 2. Refer to the periodic table and predict the empirical formula for each of the following halides given the formula of magnesium chloride MgCl2. (a) magnesium fluoride __________ (b) calcium chloride _______ (c) strontium bromide ___________ (d) barium iodide ____________ 3. A 1.000-g sample of lead shot reacted with oxygen to give 1.077 g of product. Calculate the empirical formula for the lead oxide. 4. A 0.500-g sample of tin-foil reacted with oxygen to given 0.635 g of product. Calculate the empirical formula of the tin oxide.

Explanation / Answer

Weight of Sn =0.5 g

mole of Sn = 0.5/118.71 = 0.004212
weight of the product = 0.635g

So, if all the Sn has reacted with assuming excess supply of O2(g), the weight of O2 in the product will be= 0.635-0.5 = 0.135 g

moles of O2 in the product = 0.135/16 = 0.00843

Thus, for the following reaction between Sn and O

Sn + nO2(g) ----> SnOn

molar ration of Sn and O = 1/n, determines the value of "n", in the empirical formula of the product.

So, molar ration of Sn and O from your question = 0.004212/0.00843 = 0.499 = 0.5 (approx)

Thus, the empirical formula will be Sn0.5O or rounding off is SnO2.

moles of PbO= 1.077/223.2 = 0.0048252
For 1 mole of Pb giving 1 mole of PbO,
207.2 g of Pb gives 223.2g of PbO, Hence, 1g of Pb ix expected to give, 223.2/207.2 = 1.077 g of PbO.
Hence, the empirical formula is PbO