Percent Yield

    1) When copper is heated in air, copper(II) oxide is formed. In an experiment, 1.50 g copper was heated to yield 1.76 g copper(II) oxide. What is the percent yield?

(a) 1.50%

(b) 85.0%

(c) 94.0%

(d) 100%

(e) 117%

 

    2) Magnesium hydroxide is produced by reacting magnesium oxide with excess water. If the reaction has an expected yield of 81%, how much magnesium oxide should be reacted to produce 98.0 g of magnesium hydroxide?

    MgO(s) + H₂O(l) Mg(OH)₂(s)

(a) 175 g

(b) 83.6 g

(c) 67.7 g

(d) 121 g

(e) 77.6 g

 

    3) The reaction below has an expected yield of 58%. How much hydrochloric acid should be reacted with excess oxygen to produce 44.0 g of chlorine gas?

4HCl(aq) + O₂(g)    2Cl₂(g) + 2H₂O(l)

(a) 73.7 g

(b) 75.8 g

(c) 26.2 g

(d) 45.2 g

(e) 78.0 g

 

    4) If you react 8.60 g of antimony with 11.4 g of iodine and recover 10.9 g of antimony iodide, what is the percent yield of antimony iodide?

2Sb(s) + 3I₂(s) 2SbI₃(s)

(a) 30.7%

(b) 127%

(c) 72.7%

(d) 95.6%

(e) 54.5%

 

    5) Calcium oxide and water are produced by heating calcium hydroxide. If the reaction has an expected yield of 60%, how much calcium hydroxide should be reacted to produce 115 g of calcium oxide?

Ca(OH)₂(aq) CaO(s) + H₂O(l)

(a) 254 g

(b) 152 g

(c) 145 g

(d) 192 g

(e) 92.1 g

 

    6) If you react 5.60 g of ammonia with 31.7 g of copper oxide and recover 3.48 g of nitrogen gas, what is the percent yield of nitrogen gas?

2NH₃(aq) + 3CuO(s) N₂(g) + 3Cu(s) + 3H₂O(l)

(a) 75.5%

(b) 62.1%

(c) 11.0%

(d) 93.5%

(e) 9.33%

 

    7) If you react 14.1 g of hydrazine with 15.6 g of dinitrogen tetroxide and recover 13.8 g of nitrogen gas, what is the percent yield of nitrogen gas?

2N₂H₄(l) + N₂O₄(g) 3N₂(g) + 4H₂O(l)

(a) 75.0%

(b) 88.5%

(c) 91.0%

(d) 46.5%

(e) 97.2%

 

    8) When silicon is reacted with chlorine gas, silicon tetrachloride is formed. In a given experiment, 1.50 g silicon was reacted to yield 7.76 g silicon tetrachloride. What is the percent yield?

(a) 100%

(b) 86%

(c) 19%

(d) 3.0%

    9) The reaction below has an expected yield of 63%. How much silicon dioxide should be reacted with excess carbon and calcium phosphate to produce 60.0 g of phosphorous?

Ca₃(PO₄)₂(s) + 3SiO₂(s) + 5C(s) 5CO(g) + 3CaSiO₃(s) + 2P(s)

(a) 175 g

(b) 95.2 g

(c) 110. g

(d) 277 g

(e) 174 g

   10) If you react 6.20 g of silicon with 5.30 g of nitrogen gas and recover 4.90 g of silicon nitride, what is the percent yield of silicon nitride?

3Si(s) + 2N₂(g) Si₃N₄(s)

(a) 47.6%

(b) 36.8%

(c) 92.5%

(d) 79.0%

(e) 42.6%

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