Volume 3

Pure elemental sulfur is odorless. The unpleasant "sulfur smell" is that of many sulfur compounds, not sulfur itself. The melting and boiling points of sulfur are 120

Both SO

The reaction of SO

The oxidation state of sulfur in SO

Sulfuric acid is the number one chemical produced worldwide. The process to make H

To make H

As already mentioned earlier in our course, H

In H

Hydrogen sulfide finds applications in analytical chemistry, paper making, organic synthesis, and separation of heavy water (deuterium oxide, D

1. Write the electronic configuration of a sulfur atom and account for the oxidation state of -2 of S in H

2. What sulfur mineral is called fool's gold? What are the formula and main application of this mineral? What are the oxidation states of the elements in fool's gold? Answer

3. Sulfur burns in air in the absence of a catalyst to give (a) exclusively SO_{2}; (b) exclusively SO_{3}; (c) a mixture of SO_{2} and SO_{3}; (d) sulfur does not burn in the absence of a catalyst. Answer

4. Write balanced equations for the reactions between (a) S and O_{2}; (b) SO_{2} and O_{2} (in the presence of a vanadium catalyst); (c) SO_{2} and H_{2}S; (d) I_{2} and H_{2}SO_{3} (SO_{2} + H_{2}O); (e) FeS and HCl; (f) H_{2}SO_{3} and MnO_{2} (products: MnSO_{4} and H_{2}O); (g) SO_{3} and H_{2}O; (h) SO_{2} and NaOH (excess); (i) SO_{3} + Ca(OH)_{2}; (j) H_{2}S and KOH (excess). Find redox reactions and identify the oxidant and the reductant. Indicate changes in the oxidation states. Answer

5. What is the contact process for making H_{2}SO_{4}? Where does the name "contact process" come from? Write chemical equations for the reactions employed in the contact process. [Answer: See section 3.4.2]

6. What is oleum? Why is the SO_{3} produced in the contact process dissolved in already existing H_{2}SO_{4} rather than reacted with water to make H_{2}SO_{4}? How is H_{2}SO_{4} made from oleum? [Answer: See section 3.4.2]

7. Both SO_{2} and SO_{3} have a pungent irritating odor. Both react with water to give the corresponding acid (sulfurous and sulfuric, respectively). However, concentrated aqueous solutions of sulfurous acid still smell SO_{2}, whereas solutions of H_{2}SO_{4} are odorless. Why? Answer

8. How much water should be used for mixing with 100 g of 30% oleum to convert it to 100% H_{2}SO_{4}? Answer

9. Sulforous acid H_{2}SO_{3} and hydrogen sulfide H_{2}S are weak acids. True or false? Answer

10. The pH of an aqueous solution of K_{2}SO_{3} is (a) approximately 7; (b) >7; (c) <7. Answer

11. A student criticized the upper equation in Figure 3-36.

I_{2} + SO_{2} + 2 H_{2}O = 2 HI + H_{2}SO_{4}

He insisted that since SO_{2} reacts with water to give H_{2}SO_{3}, the equation should be written as follows

I_{2} + H_{2}SO_{3} + H_{2}O = 2 HI + H_{2}SO_{4}

Which of the two equations is correct? Answer

4. Write balanced equations for the reactions between (a) S and O

5. What is the contact process for making H

6. What is oleum? Why is the SO

7. Both SO

8. How much water should be used for mixing with 100 g of 30% oleum to convert it to 100% H

9. Sulforous acid H

10. The pH of an aqueous solution of K

11. A student criticized the upper equation in Figure 3-36.

He insisted that since SO

I

Which of the two equations is correct? Answer