Autumn Semester. Basic Chemistry for Engineering/ Fundamental Inorganic Chemistry Final Exam. 18 February Time: 60 minutes

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1 Basic Chemistry Final Exam 1 Name: Student number: Instructions: Autumn Semester Basic Chemistry for Engineering/ Fundamental Inorganic Chemistry Final Exam 18 February 2013 Time: 60 minutes Answer any 4 questions out of 5 possible questions. You may answer more than 4 questions if you wish. Your marks will be taken from your top 4 questions. Show all relevant working. Write all answers and final working in pen. Give your answers to an appropriate number of significant figures. 9 pages including: 1 top page, 1 data page, 1 periodic table, 5 question pages, 1 page for rough working Hand in all pages at the end of the exam. Permissible materials: Calculator. English or English bilingual Dictionary.

2 Basic Chemistry Final Exam 2 Avagadro number x Equations and Data pv = nrt where p = pressure, V = volume, n= no. of moles, R = ideal gas constant T = temperature R = J K 1 mol 1 or R = L atm K 1 mol 1 H rxn = H f products H f reactants Density of water: 1.0 g ml 1 Enthalpies of formation CH 4(g) : 74.9 kj mol 1 HCCH (g) : kj mol 1 H 2 (l) : kj mol 1 H 2 2(l) : kj mol 1 H 3 P 4(l) : 1288 kj mol 1 PCl 3(l) : 320 kj mol 1 Latent heat of fusion (heat of forming a liquid from a solid) of Na 2 CCH 3 : 22.9 kj mol 1

3 Basic Chemistry Final Exam 3

4 Basic Chemistry Final Exam 4 Question 1 A) An inventor asks a bank to invest in a new kind of heater that uses water as a fuel. He claims the engine burns water to generate heat using oxygen and a secret catalyst. He says the reaction occurs according to the following equation: 2H 2 (l) + 2(g) > 2H 2 2(l) i) Use data from the data sheet to calculate the enthalpy change, per mole of H 2, for this reaction. iii) Which of the following words best describes the above reaction? Circle the answer. exothermic concentrated dilute endothermic spontaneous iii) Do you predict the entropy change for this reaction would be positive or negative? Why? iv) Should the bank invest in this heater? Why? B) A pocket hand warmer pouch contains a supersaturated solution of 170 g sodium acetate (Na 2 CCH 3 ) dissolved in 100 ml water. When the pouch is activated, 134 g of Na 2 CCH 3 crystallises out of solution. i) Using data from the data sheet, calculate the enthalpy change of this crystallisation process. [1] _ [3]

5 Basic Chemistry Final Exam 5 Question 2 A) i) What is the chemical formula of the following compounds? (Write C n H m followed by other elements, e.g. C 2 H 4 2 ) H 3 C CH 3 N NH 2 H 3 C CH 3 CH 3 ii) Identify pairs of isomers. If no isomer exists, circle 'No isomer'. [4] H H a) b) c) d) e) Isomer with: or: No isomer No isomer No isomer No isomer No isomer [4] B) Choose your answers from the molecules bearing the following functional groups: H NH 2 Cl a) b) c) d) i) Which molecule can exist as geometrical isomers? ii) Which molecule bears the most easily-detachable functional group?

6 Basic Chemistry Final Exam 6 Question 3 A) Choose the most appropriate concentration measure from the following list to complete parts i) iv). molarity, molality, percentage by weight, percentage by volume, parts per million i) Reporting the amount of flavour syrup in a sweet drink. ii) Measuring the effect of a solute on solvent vapour pressure across a range of temperatures. iii) Calculating the volume of solution needed for a chemical reaction. iv) Reporting levels of trace pollutants in the atmosphere. [4] B) Refer to the following chart of solubility: i) Demonstrate, using calculations, whether it is, or is not, possible to make a 12M aqueous solution of potassium chloride (KCl). [3] You will need one or more of the following terms for part ii): concentrated dilute dissolve saturated precipitate ii) Na 2 S 4 is dissolved in water at 30 C until no more will dissolve. At this point, the solution is. The solution is heated to boiling which makes some Na 2 S 4. iii) Will the Na 2 S 4 solution boil at exactly 100 C? Why? [1]

7 Basic Chemistry Final Exam 7 Question 4 A) i) Why is tin used to protect the iron in 'tin' cans. Explain why. [1] ii) Explain one method of protecting metal against corrosion with one advantage and one disadvantage. [3] B) A student makes three mistakes when designing a voltaic cell. Identify the mistakes and briefly explain why they are a problem. silver (Ag) electrode wires battery wire copper (Cu) electrode Cu(N 3 ) 2 Ag(N 3 ) 2 i) ii) iii) [6]

8 Basic Chemistry Final Exam 8 Question 5 A) Explain what effect the following changes will make to the rate of a reaction and why: i) heating the reaction: ii) diluting the reaction: iii) using a catalyst: [4] B) i) Chemists rarely perform chemical reactions between two solids. Instead, they prefer to dissolve the solids in solvents and run the reactions in solution. Explain why, in terms of collision theory. ii) Gunpowder burns charcoal (pure carbon) as a fine powder (~0.1 mm diameter), whilst barbeques burn large pieces of charcoal (~ mm length). Explain this difference. C) According to thermodynamics calculations, wood should spontaneously react with oxygen at room temperature. Explain why wooden furniture does not spontaneously catch fire at room temperature.

9 Basic Chemistry Final Exam 9 Rough Working