AS UNIT 1, CHAPTER 11. An organic compound contains 38.4 % carbon, 4.80 % hydrogen and 56.8 % chlorine bymass. What is the empirical formula of the compound?A C2H3ClB CH3ClC C2H5ClD C3H5Cl32. Which of the following contains the greatest number of hydrogen atoms?A 2 moles of water, H2OB 1.5 moles of ammonia, NH3C 1 mole of hydrogen gas, H2D 0.5 moles of methane, CH43. Magnesium oxide reacts with dilute hydrochloric acid according to the followingequation.MgO(s) + 2HCl(aq) MgCl2(aq) + H2O(l)How many moles of magnesium oxide, MgO, are required to neutralize 20 cm3 of0.50 mol dm3 hydrochloric acid, HCl?A 0.0010B 0.0050C 0.010D 0.0204. Hydrogen and oxygen react according to the following equation.2H2(g) + O2(g) 2H2O(g)If all volumes are measured at 110C and one atmosphere pressure, the volume of steamproduced after 50 cm3 of hydrogen react completely with 25 cm3 of oxygen is

A 25 cm3B 50 cm3C 75 cm3D 100 cm35. Hydrogen peroxide decomposes on heating as follows:2H2O2 2H2O + O2What mass of hydrogen peroxide is required to give 16 g of oxygen gas?A 8.5 gB 17 gC 34 gD 68 g

6. The equation for the dehydration of cyclohexanol, C6H11OH, to cyclohexene, C6H10 is:C6H11OH C6H10 + H2O50.0 g of cyclohexanol produced 32.8 g of cyclohexene.[Molar masses / g mol1 : cyclohexanol = 100; cyclohexene = 82]Calculate the percentage yield of cyclohexene.A 32.8 %B 40.0 %C 65.6 %D 80.0 %

7. The human body contains around 0.025 g of iodine molecules, I2. Which of thefollowing shows the number of iodine atoms in 0.025 g of I2?The Avogadro constant is 6.02 1023 mol1.

A 0.025 x 6.02 x 1023 126.9

B 0.025 x 6.02 x 1023 253.8

C 253.8 x 6.02 x 1023 0.025

D 126.9 x 6.02 x 1023 0.025 8. The compound butane hasA the empirical formula C4H10 and the molecular formula C2H5.B the empirical formula C2H5 and the molecular formula C4H10.C the empirical formula C2H5 and the molecular formula CnH2n+2.D the empirical formula CnH2n+2 and the molecular formula C4H10.9. For the oxidation of ammoniaa NH3 + b O2 c NO + d H2Othe values of the coefficients in the balanced equation areA a = 2, b = 3, c = 2 and d = 3B a = 4, b = 7, c = 4 and d = 4C a = 4, b = 5, c = 4 and d = 6D a = 6, b = 7, c = 6 and d = 910. The Avogadro constant is 6.0 1023 mol1. Therefore the number of atoms in 1 mol ofcarbon dioxide isA 2.0 1023B 6.0 1023C 1.2 1024D 1.8 1024

11. The equation for the complete combustion of octane is2C8H18 + 25O2 16CO2 + 18H2O(a) The mass of 10 mol of octane is A) 0.66 kgB )1.14 kgC)2.10 kgD)2.28 kg

(b) The volume of 1 mol of any gas (measured at room temperature and pressure)is 24 dm3. Hence the volume of oxygen (measured at room temperature andpressure) required for the complete combustion of 10 mol of octane isA) 240 dm3B) 300 dm3C) 3000 dm3D) 6000 dm3

12. In 2006, the concentration of carbon dioxide in the atmosphere was 382 ppm. This isequivalent toA 0.00382%B 0.0382%C 0.382%D 3.82%13. A compound was analysed and found to contain 1.45 g C, 0.482 g H,1.69 g N [Relative atomic masses: C = 12; H = 1; N = 14]The empirical formula of the compound isA CH3NB CH4NC CH5ND C2H4N14. 1 g of aluminium sulfate, Al2(SO4)3, was dissolved in water.Calculate the number of sulfate ions, SO42, present in the solution formed. [ Assume the molar mass of Al2(SO4)3 is 342 g mol1 and the Avogadro Constant is 6 1023 mol1.]A 3 1021B 1 1022C 3 1022D 9 1022 15. Calculate the mass of calcium hydroxide, Ca(OH)2, present in 100 cm3 of a0.100 mol dm3 solution.[Assume the molar mass of Ca(OH)2 is 74.0 g mol1.]A 0.570 gB 0.740 gC 1.85 gD 3.70 g16. Sodium hydrogensulfate, NaHSO4, reacts with sodium hydroxide, NaOH, as shown below.NaHSO4(aq) + NaOH(aq) Na2SO4(aq) + H2O(l)0.0100 mol of sodium hydrogensulfate is neutralized with dilute sodium hydroxide,concentration 0.200 mol dm3.Calculate the volume of sodium hydroxide required.A 20.0 cm3B 50.0 cm3C 100 cm3D 500 cm317. Which of the following gas samples occupies the greatest volume at the sametemperature and pressure?[Relative atomic masses: H = 1; C = 12; O = 16; F = 19; Ne = 20]A 1 gram of ethaneB 1 gram of oxygenC 1 gram of fluorineD 1 gram of neon18. A sample of gas was prepared for use in helium-neon lasers. It contained 4 g of heliumand 4 g of neon. What is the ratio of helium atoms to neon atoms in the sample?A 1 : 1B 2.5 : 1C 1 : 5D 5 : 119. The overall equation for the reaction between sulfur and oxygen to form sulfur trioxideis shown below.2S(s) + 3O2(g) 2SO3(g)0.9 mol of O2(g) reacted completely with excess sulfur. What volume, in dm3, ofsulfur trioxide would form?[Assume the molar gas volume = 24 dm3 mol1]A (0.9 3/2) 24B (0.9 3/2) 24C (0.9 2/3) 24D (0.9 2/3) 2420. Which of these solutions does not contain the same total number of ions as the others?

A 10.00 cm3 of 0.100 mol dm3 NaCl(aq)B 20.00 cm3 of 0.050 mol dm3 NaCl(aq)C 20.00 cm3 of 0.050 mol dm3 MgCl2(aq)D 13.33 cm3 of 0.050 mol dm3 MgCl2(aq)

21. A molecule isA a group of atoms bonded by ionic bonds.B a group of atoms bonded by covalent bonds.C a group of ions bonded by covalent bonds.D a group of atoms bonded by metallic bonds.22. The relative atomic mass is defined asA the mass of an atom of an element relative to 1/12 the mass of a carbon-12 atom.B the mass of an atom of an element relative to the mass of a hydrogen atom.C the average mass of an element relative to 1/12 the mass of a carbon atom.D the average mass of an atom of an element relative to 1/12 the mass of a carbon-12 atom.23. The definition of the mole isA the amount of any substance which occupies a volume of 24 dm3 at room temperature and pressure.B the amount of any substance containing the same number of identical entities asthere are in exactly 12 g of the carbon-12 isotope.Cthe number of atoms in exactly 12 g of the carbon-12 isotope.D the number of molecules in exactly 2 g of hydrogen at room temperature andpressure.24. The concentration of blood glucose is usually given in millimoles per dm3 ormmol dm3. A reading of 5.0 mmol dm3 is within the normal range. Glucose has amolar mass of 180 g mol1. What mass of glucose dissolved in 1 dm3 of blood wouldgive this normal reading?A 0.090 gB 0.18 gC 0.90 gD 9.0 g(Jan 2012)

25. When aqueous solutions of barium chloride and potassium sulfate are mixed, a whiteprecipitate forms. The ionic equation for the reaction isA K+(aq) + Cl (aq) KCl(s)B K2+(aq) + 2Cl (aq) KCl2(s)C Ba+(aq) + SO4 (aq) BaSO4(s)D Ba2+(aq) + SO42 (aq) BaSO4(s)

26. Which of the following processes has the highest atom economy?A Making poly(ethene) from ethene.B Making ethene from eicosane, C20H42.C Making chloromethane from methane.D Making magnesium chloride from magnesium and hydrochloric acid.

27.

28. Nickel(II) sulfate is prepared by adding an excess of nickel(II) carbonate to 0.010 mol of dilute sulfuric acid.NiCO3(s) + H2SO4(aq) NiSO4(aq) + H2O(l) + CO2(g)Solid nickel(II) sulfate crystals are produced with a 20% yield. How many moles of nickel(II) sulfate crystals are obtained?A 0.001B0.002C 0.010D 0.05029. When 0.635 g of Cu (RAM = 63.5) is added to an excess of silver nitrate solution, 2.158g of Ag (RAM = 107.9) form. The ionic equation for the reaction isA Cu(s) + Ag2+(aq) Cu2+(aq) + Ag(s)B Cu(s) + Ag+(aq) Cu+(aq) + Ag(s)C 2Cu(s) + Ag2+(aq) 2Cu+(aq) + Ag(s)D Cu(s) + 2Ag+(aq) Cu2+(aq) + 2Ag(s)(Jan 2013)30. The European Union has set a limit of 3.13 ppm for the proportion of the toxic gas carbon monoxide in the air that we breathe. This is equivalent toA 3.13%B 0.0313%C 0.000313%D 0.00000313%31. For drivers in the UK, the legal limit of the concentration of ethanol (molar mass46 g mol1) in the blood is 80 mg per 100 cm3. This is equivalent to a concentration ofA 17.4 mol dm3B 1.74 mol dm3C 0.0174 mol dm3D 0.00174 mol dm332. An important reaction which occurs in the catalytic converter of a car is2CO(g) + 2NO(g) 2CO2(g) + N2(g)when 500 cm3 of CO reacts with 500 cm3 of NO at 650 C (the operating temperature of the catalyst) and at 1 atm, the total volume of gases produced at the same temperature and pressure isA 500 cm3B 750 cm3C 1000 cm3D impossible to calculate without knowing the molar volume of gases under theseconditions.33. When a solution of barium chloride is added to sulfuric acid, a white precipitate is formed. The ionic equation (including state symbols) for this reaction isA H+(aq) + Cl(aq) HCl(s)B Ba+(aq) + SO4(aq) BaSO4(s)C Ba2+(aq) + 2SO4(aq) Ba(SO4)2(s)D Ba2+(aq) + SO42(aq) BaSO4(s)34. Ethanol (46 g mol1) is prepared by the hydration of ethane (molar mass 28 g mol1):C2H4 + H2O C2H5OHIn a typical process 28 tonnes of ethene produces 43.7 tonnes of ethanol. The percentage yield of ethanol in this process isA 64%B 95%C 100%D 156%(June 2011)35. A solution contains 66 ppm of a solute. Mass of solute dissolved in 1 kg of solution isA 66 gB 0.66 gC0.066 gD 0.000066 g36. Complete combustion of 50 cm3 of a hydrocarbon vapour gave 350 cm3 of carbon dioxide, both gas volumes being measured at the same temperature and pressure. The formula of the hydrocarbon could beA C8H18B C7H16C C6H14D C5H1237. Which of the following statements is true? The Avogadro constant is the number ofA grams of any element which contains 6.02 1023 atoms of that element.B atoms contained in one mole of any element.C atoms contained in one mole of any monatomic element.D particles (atoms, molecules or ions) required to make one gram of a substance.

38. A compound Z contains, by mass, 26.7% carbon, 2.2% hydrogen, and 71.1% oxygen.The empirical formula of Z isA CHO2B C2H2O4C CHOD C2H2O239. Equation representing the reaction between copper(II) oxide and dilute sulfuric acid isCuO(s) + H2SO4(aq) CuSO4(aq) + H2O(l)The ionic equation for the reaction isA Cu2+(s) + SO42(aq) CuSO4(aq)B O2(s) + H2SO4(aq) H2O(l) + SO42(aq)C CuO(s) + 2H+(aq) Cu2+(aq) + H2O(l)D CuO(s) + H2SO4(aq) Cu2+SO42(aq) + H2O(l)(May 2012)

40. Magnesium chloride can be made by reacting solid magnesium carbonate, MgCO3, withdilute hydrochloric acid.(a) Write an equation for the reaction, including state symbols.(2)

(b) Give TWO observations you would make when the reaction is taking place.(2)

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(c) In an experiment to make crystals of hydrated magnesium chloride, MgCl2.6H2O, magnesium carbonate was added to 25 cm3 of hydrochloric acid with concentration 2.0 mol dm3. The molar mass of magnesium carbonate is 84.3 g mol1.

(i) How many moles of acid are used in the reaction?(1)

(ii) What mass of magnesium carbonate, in grams, reacts with this amount of acid?(1)

(iii) Suggest why slightly more than this mass of magnesium carbonate is used in practice.(1)

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(iv) How would you separate the magnesium chloride solution from the reaction mixture in (iii)?(1)

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(v) The magnesium chloride solution was left to crystallise. The crystals were separated and dried carefully. A sample of 3.75g of hydrated crystals, MgCl2.6H2O, which have molar mass 203.3 g mol1, was obtained. Calculate the percentage yield of this reaction.(2)

(vi) Give ONE reason why the yield of crystals is less than 100%, even when pure compounds are used in the preparation.(1)

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............................................................................................................................................................(d) Blood plasma typically contains 20 parts per million (ppm) of magnesium, by mass.(i) Calculate the mass of magnesium, in grams, present in 100 g of plasma.(1)

(ii) Magnesium chloride can be used as a supplement in the diet to treat patients with low amounts of magnesium in the blood. Suggest ONE property which makes it more suitable for this purpose than magnesium carbonate.(1)

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(Total for Question 40 = 16 marks)41. Sulfamic acid is a white solid used by plumbers as a limescale remover. (a) Sulfamic acid contains 14.42% by mass of nitrogen, 3.09% hydrogen and 33.06% sulfur. The remainder is oxygen.(i) Calculate the empirical formula of sulfamic acid.(3)

(ii) The molar mass of sulfamic acid is 97.1 g mol1. Use this information to deduce the molecular formula of sulfamic acid.(1)

(b) A solution of sulfamic acid contains hydrogen ions. The hydrogen ions react with magnesium to produce hydrogen gas. In an experiment, a solution containing 5.5 103 moles of sulfamic acid was reacted with excess magnesium. The volume of hydrogen produced was 66 cm3, measured at room temperature and pressure.(i) Draw a labelled diagram of the apparatus you would use to carry out this experiment, showing how you would collect the hydrogen produced and measure its volume.(2)

(ii) Calculate the number of moles of hydrogen, H2, produced in this reaction.[The molar volume of a gas is 24 dm3 mol1 at room temperature and pressure](1)

(iii) Show that the data confirms that each mole of sulfamic acid produces one mole of hydrogen ions in solution.(2)

(c) Plumbers use sulfamic acid powder for descaling large items such as boilers. Sulfamic acid acts as a descaler because the hydrogen ions react with carbonate ions in limescale. (i) Write an ionic equation for the reaction of hydrogen ions with carbonate ions. State symbols are not required.(1)

(ii) Suggest ONE reason why sulfamic acid is considered less hazardous than hydrochloric acid as a descaler.(1)

...............................................................................................................................................................................................................................................................................................................(Total for Question 41 = 11 marks) (Jan, 2010)42. (a) Coral reefs are produced by living organisms and predominantly made up of calcium carbonate. It has been suggested that coral reefs will be damaged by global warming because of the increased acidity of the oceans due to higher concentrations of CO2.(i) Write a chemical equation to show how the presence of carbon dioxide in waterresults in the formation of carbonic acid. State symbols are not required.(1)

(ii) Write the ionic equation to show how acids react with carbonates.State symbols are not required.(2)

(b) One method of determining the proportion of calcium carbonate in a coral is to dissolve a known mass of the coral in excess acid and measure the volume of CO2 formed. In such an experiment, 1.13 g of coral was dissolved in 25 cm3 of HCl (an excess) in a conical flask. When the reaction was complete, 224 cm3 of CO2 had been collected over water using a 250 cm3 measuring cylinder.(i) Draw a labelled diagram of the apparatus that could be used to carry out this experiment.(2)

(ii) Suggest how you would mix the acid and the coral to ensure that no CO2 escaped from the apparatus.(1)

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(iv) Complete the equation below for the reaction between CaCO3 and HCl by inserting the missing state symbols. (1)

CaCO3(. . . . . . . . . . . . . .) + 2HCl(. . . . . . . . . . . . . .) CaCl2(. . . . . . . . . . . . . .) + H2O(l) + CO2(. . . . . . . . . . . . . .)(v) Calculate the mass of 1 mol of calcium carbonate.[Assume relative atomic masses: Ca = 40, C = 12, O = 16.](1)

(vi) Use your data and the equation in (iv) to calculate the mass of calcium carbonate in the sample and the percentage by mass of calcium carbonate in the coral. Give your final answer to three significant figures.(2)

(vii) When this experiment is repeated, the results are inconsistent. Suggest a reason for this other than errors in the procedure, measurements or calculations.(1)

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43. (Total for Question 43 = 7 marks)(Jan, 2012)44.

(Total for Question 44 = 17 marks)(Jan, 2013)45.

(Total for Question 45 = 7 marks)(June, 2011)46.

(Total for Question 46 = 9 marks)(June, 2012)