chemistry
Extra Points: 20 pts max.
• The extra points will be added to your lowest score Exam amongst Exam I, Exam II and Exam III (Exam IV is not included).
• You can only obtain a full score if you explain in detail (be organized!) all your answers. If you write only the final answer, you will not get the full score.
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1. Household bleach (NaOCl) is really a solution of sodium hypochlorite in water. It is made by reacting chlorine gas and sodium hydroxide, as shown in the unbalanced chemical equation below:
NaOH (aq) + Cl2 (g) → NaOCl (aq) + NaCl (aq) + H 2O (l) A student bubbles 83.0g of chlorine gas into an excess of aqueous sodium hydroxide. After analyzing his products, he determines that 22.0 grams of bleach are actually made.
(a) What is the oxidation number of chlorine in bleach (NaOCl)? (b) Is this reaction above redox? Explain. (c) What is the percent yield of this reaction?
2. Calculate the mass of the precipitate formed when 2.27 L of 0.0820 M Ba(OH) 2 are mixed with 3.06 L of 0.0664 M Na2SO4. 3. A 6.55 g sample of aniline (C6H5NH2, molar mass = 93.13 g/mol) was combusted in a bomb calorimeter. If the temperature rose by 32.9°C, use the information below to determine the heat capacity of the calorimeter. 4 C6H5NH2(l) + 35 O2(g) → 24 CO2(g) + 14 H2O(g) + 4 NO2(g) ∆H°rxn= -1.28 × 10
4 kJ 4. A 200 mL flask contained oxygen at 200 mmHg, and a 300 mL flask contained nitrogen at 100 mmHg. The two flasks were then interconnected so that gases flowed together in the combined volume. Assuming no change in temperature, (a) what was the partial pressure of each gas in the final mixture and (b) what was the total pressure? Assume no reactions occur between O2 and N2 in this process.
5. Aluminum reacts with chlorine gas to form aluminum chloride:
2Al(s) + 3Cl2 (g) → 2AlCl3 (s) What minimum volume of chlorine gas (at 298 K and 225 mmHg) is required to completely react with 7.85 g of aluminum?.
6. Calculate the root-mean-square, urms, and average kinetic energy of a fluorine molecule at 25 °C.