Farr High School NATIONAL 5 CHEMISTRY Unit 1 Chemical Changes and Structure ANSWERS Question Booklet (UPDATED MAY 2017) 1
Rates of Reaction 1. Explain how the following would affect the rate of the reaction between 1.0 g of magnesium ribbon and an excess of 1.0 mol l -1 of hydrochloric acid at room temperature. (a) (b) (c) Using 1.0 g of magnesium powder. Faster as there is an increased surface area so more surfaces for collisions to occur on. Using acid that has been stored in a fridge. Slower as the temperature is lower so the molecules have less energy to collide with and so there are fewer successful collisions. Using 0.5 mol l -1 acid. Slower as the concentration is lower and so there are less molecules able to collide. 2. A pupil wanted to record data that would allow her to follow the speed of the reaction between zinc and hydrochloric acid. List three ways in which she could do this. 1. Record the mass of the container and contents throughout 2. collect the gas released by syringe 3. collect the gas released by displacement of water 3. Look at the graph below and answer the following questions: a) What is the volume of gas produced after 20 seconds? 52 ml b) What is the final volume of gas produced? 75 ml c) At what time is the reaction complete (i.e. when it finished)? 60 s 2
4. The graph below shows how the volume of hydrogen gas given off changed with time during a reaction between pieces of zinc and dilute sulphuric acid. a) At what time was the reaction complete? 60 s b) Calculate the average rate of reaction over the first 20 second time period. 1.25 cm 3 s -1 c) Calculate the average rate of reaction between 20 seconds and 40 seconds. 0.4 cm 3 s -1 5. A student carried out three experiments involving the reaction of magnesium with dilute acid. They measured the volume of hydrogen given off. The same mass of magnesium and volume of acid were used each time. A curve obtained for experiment 1 is drawn on the graph. Copy the above graph and draw 2 curves on the same axes to show the curves that would be obtained for experiments 2 and 3. Label each curve clearly. 3
Mass of CO2 (g) 6. Jean carried out an investigation into the rate of reaction of marble chips with dilute hydrochloric acid. She noted the loss in mass as carbon dioxide was given off, taking readings every minute. Her table of results is given below: a) Draw the experimental arrangement for measuring the rate of the reaction. Mass loss apparatus (conical flask + contents on scales) b) Draw a graph of the results. 6 5 Reaction rate 4 3 2 1 0 0 1 2 3 4 5 6 7 8 Time (mins) c) Calculate the average rate over (i) the first 4 minutes? 1.03 g min -1 (ii) the full 8 minutes? 0.63 g min -1 7. William and Sarah carried out an experiment to investigate the rate of reaction between 3.0g of calcium carbonate and an excess of 1 mol l -1 of hydrochloric acid. They monitored the reaction by measuring the volume of gas produced over time. (a) Name the gas released in the reaction. Carbon dioxide (b) Draw the apparatus required to carry out the experiment. Conical flask with rubber bung, delivery tube and gas syringe (including plunger and scale on syringe) must be clear path for gas to flow into syringe (c) The table below shows the results obtained. Draw a line graph of these results. Time (s) Volume of gas (cm 3 ) 0 0 10 20 20 40 30 56 40 70 50 82 60 90 70 96 80 100 90 102 100 102 4
(d) (e) (f) (g) Calculate the rate of reaction (i) over the first 20 seconds 2 cm 3 s -1 (iii) between 40 and 60 seconds 1 cm 3 s -1 Why does the rate of the reaction decrease over time? As the reactants are used up there are less collisions At what time after the start did the reaction finish? 90 seconds The reaction was repeated, again using 1.5 g of calcium carbonate and an excess of 1.0 mol l -1 of hydrochloric acid. Draw a line on the graph to represent the results that you would expect for this experiment. The graph would level off at 52 cm 3 Atomic Structure and Bonding Related to Properties of Materials 1. Atoms are made up of protons, neutrons and electrons. The diagram below shows a model of an atom. Copy the diagram and label parts (a), (b) and (c). a proton/neutron, b - neutron/proton, c - electron 2. Copy and complete the table to show the mass and charge of protons, neutrons and electrons. particle mass charge proton 1 amu +1 neutron 1 amu 0 electron Negligible (0) -1 5
3. The elements in the periodic table can be split into groups. Four of these groups are shown in the diagram below. Which group do the following elements belong to? a) sodium b) chlorine c) neon d) argon alkali metals halogens noble gases noble gases e) bromine f) iron g) potassium h) copper halogens transition metals alkali metals transition metals 4. An element has a mass number of 23 and an atomic number of 11. How many electrons are there in its atoms? 11 5. Look at the nuclide notation for the following atoms and write down the numbers of protons, electrons and neutrons in each one. Protons 3 12 17 29 79 electrons 3 12 17 29 79 neutrons 4 12 18.5 34.5 50 6. Name the element which has the following numbers of particles. a) 26 electrons, 29 neutrons, 26 protons iron b) 53 protons, 74 neutrons iodine c) 2 electrons (neutral atom) helium d) 0 neutrons hydrogen 6
7. Using a copy of the periodic table, copy and complete the table below. Nuclide notation Element Atomic Number Mass Number Protons Neutrons Electrons 56 26 Fe Iron 26 56 26 30 26 31 15P Phosphorus 15 31 15 16 15 20 10Ne Neon 10 20 10 10 10 64 29Cu Copper 29 63.5 (64) 29 35 29 39 19K Potassium 19 39 19 20 19 14 7N Nitrogen 7 14 7 7 7 108 47Ag Silver 47 108 47 61 47 1 1H Hydrogen 1 1 1 0 1 244 94Pu Plutonium 94 244 94 150 94 8. Copper has two isotopes, copper-63 and copper-65. (a) What are isotopes? Atoms of an element with the same atomic number but different mass numbers (b) If the relative atomic mass of copper is given as 63.5, which isotope is in abundance? 63 9. Protium, deuterium and tritium are all isotopes of hydrogen. Their nuclide notations are shown below. (a) (b) How are the isotopes of hydrogen similar? Same number of protons and electrons (atomic number) How are the isotopes of hydrogen different? Different number of neutrons (mass number) 10. Why are atoms electrically neutral? Because they have equal numbers of positive protons and negative electrons 7
11. Complete the diagrams below to show the electron configurations of the atoms. (Helium 2 electrons, Oxygen 8 electrons, Sulphur 16 electrons, Potassium 19 electrons) 12. What is meant by an ion? An atom or molecule with an inequal number of protons and electrons and therefore an overall positive or negative charge. 13. Describe (a) how a sodium atom becomes a sodium ion (Na + ). It loses 1 electron from its outer electron shell (b) how a chlorine atom becomes a chlorine ion (Cl - ). It gains 1 electron to complete its outer electron shell (c) why argon does not form ions. It already has a full outer electron shell and so is stable and unwilling to form ions 8
14. Use a copy of the periodic table and your knowledge of ions to complete the following table. Nuclide notation Element Protons Neutrons Electrons 56 3+ 26 Fe Iron 26 30 23 28Ni 59 2+ Nickel 28 31 26 207 2+ 82Pb Lead 82 125 80 16 2-8O Oxygen 8 8 10 23 + 11Na Sodium 11 12 10 40 2+ 20Ca Calcium 20 20 18 119 50Sn Tin 50 69 50 197 3+ 79Au Gold 79 118 76 15. (a) What is meant by the valency of an atom? The number of unpaired electrons in the atoms outer shell (b) What is the valency of the following atoms? (i) magnesium (ii) bromine (iii) calcium (iv) oxygen (v) sodium 2 1 2 2 1 16. Oxygen forms diatomic molecules. (a) What is meant by a diatomic molecule? A molecule that contains 2 atoms (b) What type of bonding takes place in oxygen molecules? Covalent molecular (double) 9
17. Draw dot and cross diagrams to show the outer electrons in the following covalent chemicals. For each molecule, suggest the likely shape. (a) fluorine F 2 (b) carbon dioxide CO 2 (c) ammonia NH 3 (d) methane CH 4 18. (a) Give the names of two chemicals which form covalent networks. Carbon (diamond/graphite), boron, silicon (b) How do the melting and boiling points of chemicals which form covalent networks differ from those which form discrete covalent molecules? When melting covalent networks you must break covalent bonds but when melting covalent molecules you only need to break the weaker intermolecular forces 19. Describe how lithium atoms combine with bromine atoms to form lithium bromide. You should use diagrams to help you. Ionic lattice 10
20. Substance Electrical conductor Solution in Solid State Liquid State water State at 25 o C A yes yes insoluble liquid B no yes soluble solid C no no insoluble solid D yes yes insoluble solid E no no insoluble liquid From the table above, identify the substance which could be :- a) hexane b) candle wax (C 20 H 42 ) c) iron E C D d) sodium chloride e) mercury B A 21. Look at the following information about potassium fluoride: Melting point 857 o C Boiling point 1502 o C Electrical conductor as a solid no Electrical conductor as a liquid or in solution yes Suggest the type of bonding present in potassium fluoride and give two pieces of evidence from the information above to support your answer. Ionic: High m.p./b.p. due to strong ionic bonds being broken Conducts when molten/in solution but not as a solid as ions are not free to move 22. Give the formula for the following covalent compounds: a) carbon monoxide b) sulphur dioxide CO SO 2 c) carbon tetrafluoride d) dinitrogen trioxide CF 4 N 2 O 3 e) nitrogen monoxide f) nitrogen trihydride NO NH 3 23. Write down the chemical formula for the following ionic compounds: a) sodium chloride b) sodium hydroxide NaCl NaOH c) calcium oxide d) calcium chloride CaO CaCl 2 e) hydrogen chloride f) magnesium fluoride HCl MgF 2 g) iron (III) oxide h) potassium nitride Fe 2 O 3 K 3 N i) copper (II) chloride j) aluminium iodide CuCl 2 AlI 3 k) lithium chloride l) aluminium oxide LiCl Al 2 O 3 m) barium sulphate n) aluminium nitrate BaSO 4 Al(NO 3 ) 3 o) magnesium carbonate p) sodium permanganate MgCO 3 NaMnO 4 11
24. Write down the ionic formula for the following compounds: a) iron (II) chloride b) copper (II) oxide Fe 2+ (Cl - ) 2 Cu 2+ O 2- c) magnesium sulphide d) aluminium nitride Mg 2+ S 2- Al 3+ N 3- e) lithium nitrate f) magnesium nitrate Li + - NO 3 Mg 2+ (NO - 3 ) 2 g) sodium sulphate h) aluminium phosphate (Na + 2- ) 2 SO 4 Al 3+ 3- PO 4 i) barium carbonate j) calcium hydroxide Ba 2+ 2- CO 3 Ca 2+ (OH - ) 2 k) ammonium chloride l) potassium sulphite NH + 4 Cl - (K + 2- ) 2 SO 3 m) ammonium phosphate n) iron (II) permanganate (NH + 3-4 ) 3 PO 4 Fe 2+ (MnO - 4 ) 2 o) sodium phosphate p) aluminium nitrate (Na + 3- ) 3 PO 4 Al 3+ (NO - 3 ) 3 12
Formulae and Reaction Quantities 1. Balance the following equations: a) SnO 2 + 2H 2 Sn + 2H 2 O b) 3KOH + H 3 PO 4 K 3 PO 4 + 3H 2 O c) 2KNO 3 + H 2 CO 3 K 2 CO 3 + 2HNO 3 d) Na 3 PO 4 + 3HCl 3NaCl + H 3 PO 4 e) TiCl 4 + 2H 2 O TiO 2 + 4HCl f) C 2 H 6 O + 3O 2 3CO 2 + 3H 2 O g) Fe + 3HC 2 H 3 O 2 Fe(C 2 H 3 O 2 ) 3 + 3/2H 2 h) 2NH 3 + 5/2O 2 2NO + 3H 2 O i) B 2 Br 6 + 6HNO 3 2B(NO 3 ) 3 + 6HBr j) AlBr 3 + 3K 3KBr + Al k) P 4 + 6Br 2 4PBr 3 l) PbBr 2 + 2HCl 2HBr + PbCl 2 m) 2CoBr 3 + 3CaSO 4 3CaBr 2 + Co 2 (SO 4 ) 3 n) 2Na 3 P + 3CaF 2 6NaF + Ca 3 P 2 o) Li 3 PO 4 + 3NaBr Na 3 PO 4 + 3LiBr p) 2HBr + Mg(OH) 2 MgBr 2 + 2H 2 O q) Mn + 3HI 3/2H 2 + MnI 3 r) 2LiNO 3 + CaBr 2 Ca(NO 3 ) 2 + 2LiBr s) Si(OH) 4 + 4NaBr SiBr 4 + 4NaOH t) 2NaCN + CuCO 3 Na 2 CO 3 + Cu(CN) 2 13
2. For each of the following compounds calculate the gram formula mass (mass of one mole in grams). a) sodium chloride b) sodium hydroxide 58.5g 40g c) calcium oxide d) calcium chloride 56g 111g e) hydrogen chloride f) magnesium fluoride 36.5g 62.5g g) iron (III) oxide h) potassium nitride 160g 131g i) copper (II) chloride j) aluminium iodide 134.5g 408g k) carbon dioxide l) methane 44g 16g 3. What is the mass (g) of: a) 2 moles of argon b) 0.5 moles of copper 80g 31.75g c) 3 moles of sodium chloride d) 0.2 moles of methane 175.5g 3.2g e) 10 moles of oxygen f) 0.25 moles of copper (II) oxide 320g 19.88g g) 0.01 moles of nitric acid [HNO 3 ] h) 0.25 moles of chlorine 0.63g 17.75g 4. Calculate how many moles are in: a) 14 g of nitrogen gas b) 20g of sodium 2 moles 0.87 moles c) 14.2 g of chlorine gas d) 16g of calcium 0.2 moles 0.4 moles e) 400g of copper (II) oxide f) 85g of lithium chloride 5 moles 2 moles g) 30g of aluminium sulphide h) 2.2g of carbon dioxide 0.2 moles 0.05 moles i) 84g of magnesium carbonate j) 321g of iron (III) hydroxide 1 mole 3 moles 5. Five moles of an unknown substance was found to weigh 325g. What was the gram formula mass of the substance? 65g 6. (a) A substance has a gram formula mass of 95g. Its formula is XCI 2. What could element X be? Magnesium (b) The substance X 2 O has a gram formula mass of 62 g. Identify element X. Sodium (c) A substance has the formula X(OH) 3 and a gram formula mass of 78g. Identify X. Aluminium 14
7. (a) Calculate the mass of oxygen needed to produce 20.25 g of magnesium oxide. 2Mg + O 2 2MgO 8g (b) What mass of carbon dioxide is produced when 66 g of propane is burned in air. C 3 H 8 + 10O 2 3CO 2 + 4H 2 O 198g (c) What mass of water is produced when 160g of methane burns completely in air? CH 4 + 2O 2 CO 2 + 2H 2 O 360g (d) The fuel in a dragster is called nitromethane and it burns as follows: 4CH 3 NO 2 + 3O 2 4CO 2 + 6H 2 O + 2N 2 45kg of fuel is used in each race. Calculate the mass of oxygen required to burn this mass of fuel. 17.7kg (e) What mass of iron would be produced by reducing 320 tonnes of iron (III) oxide in a blast furnace? Fe 2 O 3 + 3CO 2Fe + 3CO 2 224 tonnes (f) Calculate the mass of water produced when 8g of hydrogen burns in oxygen. 2H 2 + O 2 2H 2 O (g) 72g Calculate the mass of iron (III) sulphide produced when 2.8g of iron reacts with excess sulphur. 2Fe + 3S Fe 2 S 3 5.2g 8. What concentration of solution is obtained by dissolving: a) 5 moles of hydrogen chloride in 2 litres of solution 2.5 mol l -1 b) 0.8 moles of copper sulphate in 200 cm 3 of solution 4 mol l -1 c) 0.5 moles of lithium fluoride in 500 cm 3 of solution 1 mol l -1 d) 1.25 moles of calcium nitrate in 2000 ml of solution 2.5 mol l -1 e) 0.1 moles of nitric acid in 10 ml of solution 10 mol l -1 f) 40 moles of potassium bromide in 100 litres of solution 0.4 mol l -1 9. What volume of solution is required to make: a) 0.4 mol l -1 solution containing 1 mole of sodium hydroxide 2.5 l b) 0.1 mol l -1 solution containing 0.05 moles of magnesium chloride 0.5 l c) 20 mol l -1 solution containing 4 moles of hydrogen peroxide 0.2 l d) 0.025 mol l -1 solution containing 0.02 moles of barium nitrate 0.8 l e) 2.25 mol l -1 solution containing 0.4 moles of ammonium bromide 0.18 l f) 6 mol l -1 solution containing 0.2 moles of sulphuric acid 0.03 l 15
10. How many moles are dissolved in: a) 500 ml of 0.5 mol l -1 sodium carbonate solution 0.25 moles b) 3000 cm 3 of 2 mol l -1 barium chloride solution 6 moles c) 5 litres of 0.1 mol l -1 zinc sulphate solution 0.5 moles d) 250 cm 3 of 0.04 mol l -1 ammonium nitrate solution 0.01 moles e) 600 ml of 3 mol l -1 hydrochloric acid solution 1.8 moles f) 10 cm 3 of 0.2 mol l -1 potassium permanganate solution 0.002 moles 11. For the following, calculate the number of moles of each substance and from this, calculate the mass of solid needed to make the following solutions: a) 500 ml of a 4 mol l -1 solution of potassium chloride 2 moles = 149g b) 100 ml of a 0.4 mol l -1 solution of lithium hydroxide 0.04 moles = 0.96g c) 2 litres of a 1.6 mol l -1 solution of magnesium fluoride 3.2 moles = 200g d) 800 cm3 of a 1 mol l -1 solution of ammonium nitrate 0.8 moles = 64g e) 50 litres of a 2 mol l -1 solution of sodium carbonate 100 moles = 10,600g f) 10 ml of a 0.05 mol l -1 solution of aluminium sulphate 0.0005 moles = 0.147g g) 3 litres of a 0.6 mol l -1 solution of nickel (II) bromide 1.8 moles = 393.3g h) 25 cm3 of a 0.1 mol l -1 solution of silver (I) nitrate 0.0025 moles = 0.425g 12. What is the concentration of solution if 10g of sodium hydroxide is dissolved in 3 litres of solution? 0.08 mol l -1 13. What concentration of solution is made by dissolving 16.4 g of calcium nitrate in 250 ml of solution? 0.4 mol l -1 14. What is the concentration of 100 cm 3 of ammonium hydroxide solution containing 0.7 g of dissolved solute? 0.2 mol l -1 15. What volume of 4 mole l -1 sulphuric acid solution contains 9.8 g of solute? 0.025l 16. What volume of solution is required to make a 0.02 mol l -1 solution from 3.9 g of lithium fluoride? 7.5l 17. What volume of solution is needed to make a 0.5 mol l -1 solution from 1.32 g of ammonium sulphate? 0.02l 16
18. Use the data booklet, page 7, to calculate the percentage, by mass, of: a) carbon in carbon dioxide 27.3% b) potassium in potassium carbonate, K 2 CO 3 56.5% c) nitrogen in ammonium nitrate NH 4 NO 3 35% d) calcium in calcium hydroxide; Ca(OH) 2 54.1% e) lead in lead(ii) bromide (PbBr 2 ) 56.4% f) aluminium in aluminium oxide (Al 2 O 3 ) 52.9% g) nitrogen in urea, (NH 2 ) 2 CO 46.6% h) nitrogen, and potassium, in potassium nitrate N = 13.9% K = 38.6% i) nitrogen in ammonium sulfate 21.2% j) nitrogen, and phosphorus, in ammonium phosphate N = 28.2% P = 20.8% 17
Acids and Bases 1. What do the following pieces of information tell you about the solutions? (a) Solution A turns universal indicator red. acidic (b) Solution B has a ph of 8. alkaline (c) Solution C turns universal indicator purple. alkaline (d) Solution D has a ph of 7. neutral 2. Do the following chemicals make acidic, alkaline or neutral solutions when they dissolve in water? (a) sodium chloride (b) sugar Neutral neutral (c) hydrogen chloride (d) potassium hydroxide Acidic alkaline (e) carbon dioxide acidic 3. Explain what is meant by dissociation. Use an equation to help. The splitting of a molecule into smaller molecules/atoms/ions 4. How does the number of hydrogen ions (H + ) compare to the number of hydroxide ions (OH - ) in: a) a neutral solution? equal b) an acidic solution? Concentration of hydrogen ions is greater than the concentration of hydroxide ions c) an alkaline solution? Concentration of hydroxide ions is greater than the concentration of hydrogen ions 5. Complete the table to show the difference in properties between strong and weak acids. Property Weak acid Strong Acid Electrical conductivity Lower Higher ph higher Lower Reactivity lower higher 18
6. An alkali has a ph of 12. a) How will the concentration of hydrogen ions compare to the number of hydroxide ions in the solution? Concentration of hydrogen ions is lower than the concentration of hydroxide ions b) The solution is diluted with water. Explain what will happen to the ph of the solution. It will decrease as the number of hydrogen ions increases as more water is added and so the ph moves nearer to 7/neutral. 7. A pupil used a sensor to record the change in ph of 10 cm3 of an acid solution when an alkali solution was added a little at a time. The concentrations of the alkali and acid solutions were fixed. His results are shown in the table below. volume of alkali added (cm3) ph of resulting mixture 0.0 5.0 2.0 5.0 4.0 5.0 6.0 5.5 8.0 6.0 10.0 7.0 12.0 8.0 14.0 8.5 16.0 9.0 18.0 9.0 20.0 9.0 (a) Use his results to draw a graph on a piece of graph paper. Label the axes. Plot the points. Draw a smooth curve. 19
ph of resulting mixture ph 10 9 8 7 6 5 4 3 2 1 0 0 5 10 15 20 25 Volume of alkali added (cm 3 ) (b) Look at the graph. What would be the likely ph of the solution if the pupil added a further 2 cm3 of alkali solution? 9.0 8. Write a word equations for each of the following neutralization reactions: a) Potassium hydroxide reacting with sulphuric acid. Potassium hydroxide + sulfuric acid potassium sulfate + water b) Potassium hydroxide reacting with nitric acid. Potassium hydroxide + nitric acid potassium nitrate + water c) Potassium hydroxide reacting with hydrochloric acid. Potassium hydroxide + hydrochloric acid potassium chloride + water d) Calcium hydroxide reacting with hydrochloric acid. Calcium hydroxide + hydrochloric acid calcium chloride + water e) Magnesium oxide reacting with hydrochloric acid. Magnesium oxide + hydrochloric acid magnesium chloride + water f) Calcium hydroxide reacting with sulphuric acid. Calcium hydroxide + sulfuric acid calcium sulfate + water g) Calcium carbonate reacting with dilute sulphuric acid. Calcium carbonate + sulfuric acid calcium sulfate + water + carbon dioxide h) Calcium carbonate reacting with dilute hydrochloric acid. Calcium carbonate + hydrochloric acid calcium chloride + water + carbon dioxide i) Malachite (mainly copper carbonate) reacting with dilute sulphuric acid. Copper carbonate + sulfuric acid copper sulfate + water + carbon dioxide j) Malachite reacting with dilute hydrochloric acid. Copper carbonate + hydrochloric acid copper chloride + water + carbon dioxide 20
9. Write the word equation, a balanced formula equation and an ionic equation for the following reactions. Identify the spectator ions in the ionic equation. a) Lithium hydroxide solution and hydrochloric acid lithium hydroxide + hydrochloric acid lithium chloride + water LiOH + HCl LiCl + H 2 O Li + OH - + H + Cl - Li + Cl - + H 2 O b) Calcium hydroxide solution and sulphuric acid calcium hydroxide + sulfuric acid calcium sulfate + water Ca(OH) 2 + H 2 SO 4 CaSO 4 + 2H 2 O Ca 2+ (OH - ) 2 + (H + ) 2 SO 4 2- Ca 2+ SO 4 2- + 2H 2 O c) Barium oxide solution and nitric acid barium oxide + nitric acid barium nitrate + water BaO + 2HNO 3 Ba(NO 3 ) 2 + H 2 O Ba 2+ O 2- + 2H + NO 3 - Ba 2+ (NO 3 - ) 2 + 2H 2 O d) Iron (II) oxide powder and hydrochloric acid iron (II) oxide + hydrochloric acid iron (II) chloride + water FeO + 2HCl FeCl 2 + H 2 O Fe 2+ O 2- + 2H + Cl - Fe 2+ (Cl - ) 2 + 2H 2 O e) Calcium carbonate lumps and sulphuric acid calcium carbonate + sulfuric acid calcium sulfate + water + carbon dioxide CaCO 3 + H 2 SO 4 CaSO 4 + H 2 O + CO 2 Ca 2+ CO 3 2- + (H + ) 2 SO 4 2- Ca 2+ SO 4 2- + H 2 O + CO 2 f) Lithium carbonate solution and nitric acid lithium carbonate + nitric acid lithium nitrate + water + carbon dioxide Li 2 CO 3 + 2HNO 3 2LiNO 3 + H 2 O + CO 2 (Li + ) 2 CO 3 2- + 2H + NO 3-2Li + NO 3 - + H 2 O + CO 2 10. In a reaction magnesium carbonate powder is used to neutralise 250 cm 3 of 2 mol l -1 dilute hydrochloric acid. a) How many moles of hydrochloric acid have been used in the experiment? 0.5 moles b) The equation for the reaction is MgCO 3 (s) + 2HCl (aq) MgCl 2(aq) + H 2 O (l) +CO 2(g) Using your answer from part (a), calculate the number of moles of magnesium carbonate required to neutralise the dilute hydrochloric acid. 0.25 moles c) Using your answer from part (b), calculate the mass of magnesium carbonate required to neutralise the dilute hydrochloric acid. 21.13g 11. In a reaction calcium carbonate powder is used to neutralise 500 cm 3 of 0.5 mol l -1 dilute hydrochloric acid. a) How many moles of hydrochloric acid have been used in the experiment? 0.25 moles b) The equation for the reaction is CaCO 3 (s) + 2HCl (aq) CaCl 2(aq) + H 2 O (l) +CO 2(g) Using your answer from part (a), calculate the number of moles of calcium carbonate required to neutralise the dilute hydrochloric acid. 0.125 moles c) Using your answer from part (b), calculate the mass of calcium carbonate required to neutralise the dilute hydrochloric acid. 12.5g 21
12. In a reaction sodium carbonate powder is used to neutralise 200 cm 3 of 2 mol l -1 dilute sulphuric acid. a) How many moles of sulphuric acid have been used in the experiment? 0.4 moles b) The equation for the reaction is Na 2 CO 3(s) + H 2 SO 4(aq) Na 2 SO 4(aq) + H 2 O (l) +CO 2(g) Using your answer from part (a), calculate the number of moles of sodium carbonate required to neutralise the dilute sulphuric acid. 0.2 moles c) Using your answer from part (b), calculate the mass of sodium carbonate required to neutralise the dilute sodium acid. 21.2g 13. Calculate the concentration of sodium hydroxide if 50cm 3 of the alkali exactly neutralised 100cm 3 of 1 mol l -1 hydrochloric acid solution. 2 mol l -1 14. Calculate the volume of 0.25 mol l -1 sodium hydroxide if the alkali exactly neutralised 25 cm 3 of 0.5 mol l -1 hydrochloric acid solution. 0.05l 15. Calculate the concentration of hydrochloric acid if 100cm 3 if the acid exactly neutralised 25cm 3 of 0.5 mol l -1 sodium hydroxide solution. 0.125 mol l -1 16. Calculate the concentration of sodium hydroxide if 50cm 3 of the alkali exactly neutralised 100cm 3 of 1 mol l -1 sulphuric acid solution. 2 mol l -1 17. Calculate the volume of 0.25 mol l -1 sodium hydroxide if the alkali exactly neutralised 50 cm 3 of 0.5 mol l -1 sulphuric acid solution. 0.1l 18. Calculate the concentration of sulphuric acid if 25cm 3 if the acid exactly neutralised 25cm 3 of 0.5 mol l -1 sodium hydroxide solution. 0.5 mol l -1 22