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QUESTION 2 (12 marks) Salicylic acid reacts with ethanoic anhydride in an aqueous solution to produce acetylsalicylic acid as shown in the equation. Acetylsalicylic acid is commonly known as aspirin. a) b) Cc) d) e) O On i O C CH /&ÔøΩ CH 3 7 ÔøΩ + CÔøΩOH As = CH-CÔøΩOH I ee: CÔøΩOH 3 O salicylic acid ethanoic anhydride acetylsalicylic acid ethanoic acid (C H 05) (C H 03) (C H O0 ) (C H 0 ) Identify the type of chemical reaction used to produce aspirin. [1 mark] Write the equilibrium expression K for the reaction. [1 mark] At 20 ÔøΩC the equilibrium constant (K ) for the reaction is 2 x 10ÔøΩ. Determine whether the concentration of the reactants or products is greater at equilibrium at this temperature. [2 marks] Calculate the minimum mass of salicylic acid required to produce 500.0 mg of aspirin if the yield of aspirin 1s 45.0%. Show your working. [4 marks] mg (to three significant figures) When the reaction is heated to 40 ÔøΩC and equilibrium is re-established the concentration of acetylsalicylic acid and ethanoic acid increases. Apply Le ChatelierÔøΩs principle to predict if the forward reaction is exothermic or endothermic. Explain your reasoning. [4 marks]
QUESTION 3 (9 marks) Ethanol can be produced by the fermentation of glucose or the hydration of ethene. a) Describe the production of ethanol by fermentation of glucose by writing a balanced equation and indicating if a catalyst is required. b) Calculate the atom economy for the production of ethanol by fermentation of glucose. Atom economy = c) Interms of atom economy determine which process for the production of ethanol (i.e. hydration of ethene or fermentation of glucose) is greener. d) Identify two principles of green chemistry other than atom economy that make the production of ethanol by fermentation greener than by hydration. [3 marks] [2 marks] [2 marks] [2 marks]
QUESTION 8 Electric current id Air in Ja O and other gases in Unused Wily <7 Excess fuel gases out = Anode Electrolyte Cathode Identify the operating conditions for the hydrogen fuel cell. (A) acidic conditions with hydrogen given off as an unused gas (B) alkaline conditions with hydrogen given off as an unused gas (C) acidic conditions with hydrogen ions present in the electrolyte (D) alkaline conditions with hydrogen ions present in the electrolyte
QUESTION 16 Calculate the percentage yield of magnesium ethanoate when 8.0 moles of ethanoic acid reacts with 6.0 moles of magnesium carbonate producing 3.5 moles of magnesium ethanoate as shown in the equation. 2CH;COOH(aq) + MgCO (s) > (CH;COO) Mg(aq) + CO (g) + H5O(1) (A) 44% (B) 58% (C) 88% (D) 100%
QUESTION 19 To form ethanol biofuel in the fermentation of glucose a catalyst is used because (A) (B) (C) (D) less energy is required and the rate of reaction is increased. less energy is required and the rate of reaction is decreased. more energy is required and the rate of reaction is increased. more energy 1s required and the rate of reaction is decreased
QUESTION 5 Phosphorus pentoxide is prepared by burning phosphorus in oxygen. P4(s) + 509(g) > P4Oj0(s) Calculate the percentage yield if 10.0 g of P4Oj9 is produced when 0.200 mol of P and 0.200 mol of O are reacted. (A) 2.0% (B) 3.5% (C) 17.6% (D) 88.0%
QUESTION 4 (8 marks) Bioethanol is a renewable energy source made from biomasses such as starch and cellulosic materials. The two-step process for the conversion of starch and cellulose to bioethanol is shown. Process | Step 1 Step 2 Conversion | Production to glucose process Starch Enzymatic hydrolysis Fermentation of glucose to Easier Faster (aÔøΩamylase) of starch form bioethanol (yeast) biomass to form glucose Cellulose | Acid hydrolysis (H SO (aq) | Fermentation of glucose to Harder Slower at 320 ÔøΩC and 25 MPa) of form bioethanol (yeast) cellulose biomass to form glucose a) Identify why it is important to control the temperature during the fermentation process to produce bioethanol. [2 marks] b) Explain why cellulose is harder to convert to glucose than starch. [3 marks] c) After 48 hours of fermentation a 15% w/v glucose solution produces 37.5 g L! of ethanol. Calculate the percentage yield of ethanol. Show your working. [3 marks] Ethanol yield = % (to one decimal place)
QUESTION 23 (6 marks) The diagram represents a hydrogen fuel cell with an acid electrolyte. Proton exchange membrane a) H (g) O»(g) ! Product Z | (a) Determine the redox half-equation occurring at the anode and cathode. [2 marks] Anode half-equation: Cathode half-equation: (b) Identify product Z. [1 mark] (c) Compare the movement of electrons and hydrogen ions in the fuel cell. [3 marks] Similarity: Difference: Significance:
QUESTION 9 (4 marks) Aspirin (Cy)HgO ) can be produced from a reaction between salicylic acid (Cj;H O3) and acetic anhydride (C H O3) with ethanoic acid being a minor product. C7H6O03(s) + CyHe¢O3(aq) — CoHgOq(s) + C H4O>(aq) Calculate the mass of salicylic acid required to produce 8.25 g of aspirin if the percentage yield of the reaction is 60%. Show your working.
QUESTION 25 (7 marks) During the contact process for manufacturing sulfuric acid sulfur dioxide (SO ) and oxygen (O ) are passed over a vanadium oxide catalyst to produce sulfur trioxide (SO3). In the process the vanadium oxide undergoes the following reactions. Reaction 1: SO (g) + V 0;(s) > SO3(g) + V»O (s) Reaction 2: 2V 0 (s) + O (g) — 2V 0;(s) Overall reaction: 2SO3(g) + 05(g) —225 5 280 (g) (a) Determine the oxidation state of vanadium in V 0 (s). [1 mark] (b) Determine if vanadium in V O (s) in reaction | is acting as an oxidising or reducing agent. Explain your reasoning. [2 marks] (c) Use the reactions provided to explain why V O (s) 1s a catalyst for the overall reaction. [4 marks]
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