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Chapter 9

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HEINS09-095-117v4.qxd 12/30/06 1:58 PM Page 113<br />

- <strong>Chapter</strong> 9 -<br />

140.0 g CuSO 4 2a 1 mol<br />

159.6 g b ¢ 1 mol FeSO 4<br />

≤ a 151.9 g b = 38.1 g FeSO<br />

1 mol CuSO 4 mol<br />

4 produced<br />

Calculate the mass of unreacted Fe.<br />

140.0 g CuSO 4 2a 1 mol<br />

159.6 g b ¢ 1 mol Fe<br />

≤ a 55.85 g b = 14.0 g Fe will react<br />

1 mol CuSO 4 mol<br />

Unreacted Fe = 20.0 g - 14.0 g = 6.0 g. Therefore, at the completion of the<br />

reaction, 15.9 g Cu, 38.1 g FeSO 4 , 6.0 g Fe, and no CuSO 4 remain.<br />

47. Limiting reactant calculation<br />

CO(g) + 2 H 2 (g) ¡ CH 3 OH(l)<br />

Reaction between 40.0 g CO and 10.0 g H 2 : determine the limiting reactant by<br />

calculating the amount of CH 3 OH that would be formed from each reactant.<br />

140.0 g CO2a 1 mol<br />

28.01 g b ¢ 1 mol CH 3OH<br />

1 mol CO ≤ a 32.04 g b = 45.8 g CH<br />

mol<br />

3 OH<br />

110.0 g H 2 2a 1 mol<br />

2.016 g b ¢ 1 mol CH 3OH<br />

≤ a 32.04 g b = 79.5 g CH<br />

2 mol H 2 mol<br />

3 OH<br />

CO is limiting; H 2 is in excess; 45.8 g CH 3 OH will be produced.<br />

Calculate the mass of unreacted H 2 :<br />

140.0 g CO2a 1 mol<br />

28.01 g b ¢ 2 mol H 2<br />

1 mol CO ≤ a 2.016 g b = 5.76 g H<br />

mol<br />

2 react<br />

10.0 g H 2 - 5.76 g H 2 = 4.2 g H 2 remain unreacted<br />

48. The balanced equation is C 6 H 12 O 6 ¡ 2 C 2 H 5 OH + 2 CO 2<br />

(a) First calculate the theoretical yield.<br />

1750 g C 6 H 12 O 6 2a 1 mol<br />

180.2 g b ¢ 2 mol C 2H 5 OH<br />

≤ a 46.07 g b<br />

1 mol C 6 H 12 O 6 mol<br />

Then take 84.6% of the theoretical yield to obtain the actual yield.<br />

actual yield =<br />

1theoretical yield2184.62<br />

100<br />

= 3.2 * 10 2 g C 2 H 5 OH<br />

- 113 -<br />

= 3.8 * 10 2 g C 2 H 5 OH (theoretical yield)<br />

= 13.8 * 102 g C 2 H 5 OH2184.62<br />

100

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