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					Percent Purity, Percent Yield                                         Name: __________________________
                                                                      Date: _________________

 1. The roasting of siderite ore, FeCO3, produces iron (III) oxide:
                                      FeCO3 + O2  Fe2O3 + CO2
       a. What is the balanced equation?
           4 FeCO3 + O2  2 Fe2O3 + 4 CO2
       b. A 15.0 g FeCO3 sample is 42.0% pure. What mass of Fe2O3 can the sample produce?
           (6.30 g pure FeCO3 will react)
           4.34 g Fe2O3
       c. A second sample of FeCO3, with a mass of 55.0 g is roasted so as to produce 37.0g of Fe2O3.
           What is the percentage purity of FeCO3?
           (49.9g pure FeCO3)
           49.9g / 55.0 g * 100% = 97.6 %
       d. A 35.0 g sample of pure FeCO3 produces 22.5 g of Fe2O3. What is the percentage yield of the
           (24.1g pure Fe2O3 produced)
           22.5g / 24.1 g *100% = 93.3%
       e. What mass of siderite ore with a purity of 62.8% is needed to make 1.00 kg of Fe2O3?
           2310 g

 2. A 100. g sample of impure FeS2 is roasted to produce Fe2O3 + SO2:
                                      4 FeS2 + 11 O2  2 Fe2O3 + 8 SO2
    If 4.50 L of SO2 is collected at STP, what percentage of FeS2 is in the sample?
    (find the mass of FeS2 required to make 4.50L of SO2 = 12.1 g FeS2)

 3. ***This question is quite challenging***
    The reaction:
                                SiO2 (g) + HF (g)  SiF4 (g) + 2 H2O (g)
    produces 2.50g of H2O when 12.20g of SiO2 is treated with a small excess of HF?
        a. What is the balanced equation?
            SiO2 + 4 HF  SiF4 + 2 H2O
        b. What mass of SiF4 is formed?
        c. What mass of SiO2 is left unreacted?
        d. What is the percentage yield of SiF4?

 4. When 5.000 kg of malachite ore containing 4.30% of malachite, Cu2(OH)2CO3, is heated, the product
    is copper (II) oxide:
                                  Cu2(OH)2CO3  CO2 + CuO + H2O
        a. What is the balanced equation?
            Cu(OH)2CO3  CO2 + 2 CuO + H2O
        b. If the reaction has an 84.0% yield, how many grams of CuO are produced?
            1.30 x 102 g
        c. If the decomposition reaction has an 87.0% yield, what mass of ore containing 3.70%
            malachite is required to produce 100.0g of CuO?
            4.32 x 103 g

 5. A mine produces a silver ore named argentite, Ag2S. The ore is smelted according to the overall
                                  Ag2S + C + O2  Ag + CO2 + SO2
a. What is the balanced equation?
   Ag2S + C + 2 O2  2 Ag + CO2 + SO2
b. A 250.0 kg load of argentite ore contains 0.135% pure Ag2S. What mass of silver metal can
   be produced from the load of core?
   294 g
c. A 76.4 g test sample of ore from a new ore vein produces 0.261g of pure silver. What is the
   percentage of pure argentite in the ore?
d. A sample of pure Ag2S has a mass of 152.6 g. When smelted, the sample produces 117.4 g of
   pure Ag. What is the percentage yield of the smelting process?
e. What mass of ore containing 0.795 % Ag2S is required to produce a 50.0 kg ingot of silver
   7.22 x 106 g
f. If 89.2% of the Ag2S present is extracted from 3.50x104 kg of ore containing 1.86% Ag2S,
   what mass of silver metal can be produced?
   5.05 x 105 g

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