26.07.2021 Views

General Chemistry Principles, Patterns, and Applications, 2011

General Chemistry Principles, Patterns, and Applications, 2011

General Chemistry Principles, Patterns, and Applications, 2011

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

. If 9.00 g of nitric acid had been used in the reaction, which would be the limiting reactant?<br />

c. What is the theoretical yield in grams of nitroglycerin?<br />

d. If 9.3 g of nitroglycerin was produced from 9.0 g of nitric acid, what would be the percent yield?<br />

e. Given the data in part d, how would you rate the success of this reaction according to the criteria mentioned<br />

in this chapter?<br />

f. Derive a general expression for the theoretical yield of nitroglycerin in terms of xgrams of glycerol.<br />

2. ♦ A significant weathering reaction in geochemistry is hydration–dehydration. An example is the<br />

transformation of hematite (Fe 2 O 3 ) to ferrihydrite (Fe 10 O 15·9H 2 O) as the relative humidity of the soil<br />

approaches 100%:<br />

Fe 2 O 3 (s) + H 2 O(l) → Fe 10 O 15·9H 2 O(s)<br />

This reaction occurs during advanced stages of the weathering process.<br />

a. Balance the chemical equation.<br />

b. Is this a redox reaction? Explain your answer.<br />

c. If 1 tn of hematite rock weathered in this manner, how many kilograms of ferrihydrite would be formed?<br />

3. ♦ Hydrazine (N 2 H 4 ) is used not only as a rocket fuel but also in industry to remove toxic chromates from<br />

waste water according to the following chemical equation:<br />

4CrO 2− 4 (aq) + 3N 2 H 4 (l) + 4H 2 O(l) → 4Cr(OH) 3 (s) + 3N 2 (g) + 8OH − (aq)<br />

Identify the species that is oxidized <strong>and</strong> the species that is reduced. What mass of water is needed for the<br />

complete reaction of 15.0 kg of hydrazine? Write a general equation for the mass of chromium(III) hydroxide<br />

[Cr(OH) 3 ] produced from x grams of hydrazine.<br />

4. ♦ Corrosion is a term for the deterioration of metals through chemical reaction with their environment. A<br />

particularly difficult problem for the archaeological chemist is the formation of CuCl, an unstable compound<br />

that is formed by the corrosion of copper <strong>and</strong> its alloys. Although copper <strong>and</strong> bronze objects can survive<br />

burial for centuries without significant deterioration, exposure to air can cause cuprous chloride to react with<br />

atmospheric oxygen to form Cu 2 O <strong>and</strong> cupric chloride. The cupric chloride then reacts with the free metal to<br />

produce cuprous chloride. Continued reaction of oxygen <strong>and</strong> water with cuprous chloride causes “bronze<br />

disease,” which consists of spots of a pale green, powdery deposit of [CuCl 2·3Cu(OH) 2·H 2 O] on the surface of<br />

the object that continues to grow. Using this series of reactions described, complete <strong>and</strong> balance the<br />

following equations, which together result in bronze disease:<br />

Saylor URL: http://www.saylor.org/books<br />

Saylor.org<br />

299

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!