(b)

Describe how the following changes are brought about: (i) Pig iron into steel. (ii) Zinc oxide into metallic zinc. (iii) Impure titanium into pure titanium.

(a) Write the chemical equation for the complete combustion of butane.  (b) Why is it not advisable to use a butane stove inside a tent?

4. True or False (1) Chlorine demand is the difference between total chlorine and free chlorine (2) In raw wastewater samples, most of nitrogen is in the form of nitrate. (3) If 10 mg/L of NH3-N is converted to nitrate, the nitrate concentration is 10 mg/L as N. (4) Free chlorine consists of hypochlorous acid and hypochlorite. (5) Chloramines is a weaker disinfectant than free chlorine. (6) Na2HPO4 contributes to the orthophosphates. (7) For phosphorus analysis, the purpose of the autoclave is to kill the phosphorus bacteria which interferes colorimetric analysis. (8) Chloride is an effective disinfectant for water and wastewater treatment. (9) "Crown" corrosion is caused by the corrosive action of H₂SO4. (10) Breakpoint chlorination can be used for removal of ammonia.

Write a balanced chemical equation for the reac- tion of bromine and triolein, a triglyceride of oleic acid, CH3(CH2),CH=CH(CH,),COOH. 2.

synthesis

The bombardier beetle uses an explosive discharge as a defensive measure. The chemical reaction involved is the oxidation of hydroquinone by hydrogen peroxide to produce quinone and water:

6. The oxidation of methylhydrazine, N,H,CH,(1), by dinitrogen tetroxide, N,O,(1), was used for propulsion in the Space Shuttle orbiter. This reaction is represented by the equation 4 N,H,CH;(1) + 5 N,0,(1) → 12 H,O(g) + 9 N,(g) + 4 CO,(g) The enthalpy of formation for liquid methylhydrazine is +53 kJ/mol and the enthalpy of formation for liquid dinitrogen tetroxide is -20 kJ/mol. Calculate AH° for this reaction. KU A

(24) The gold-plating of a ceramic figurine requires a total of 2.78 g of solid gold. If the current being used is 12.7 amperes, how many minutes will it take to plate the gold figurine? You may assume that there is sufficient concentration of gold cation to complete the process. (A) 1.79 (B) 1056 (C) 5.36 VELG 14 (D) 68.1 (E) 4.57 8

The psychoactive drug methamphetamine ("speed"), which is sold as the prescription medication Desoxyn, C10H15N, under- goes a series of reactions in the body; the net result of these reac- tions is the oxidation of solid methamphetamine by oxygen gas to produce carbon dioxide gas, liquid water, and an aqueous solution of urea, CH4N₂O. Write the balanced equation for this net reaction.