The table below shows the boiling points and properties of some of the elements in Group 7 of the periodic table. Colour in aqueous solution

Transcription

1 Q. This question is about halogens and their compounds. The table below shows the boiling points and properties of some of the elements in Group 7 of the periodic table. Element Boiling point in C Colour in aqueous solution Fluorine 88 colourless Chlorine 35 pale green Bromine X orange Iodine 84 brown (a) Why does iodine have a higher boiling point than chlorine? Tick one box. Iodine is ionic and chlorine is covalent Iodine is less reactive than chlorine The covalent bonds between iodine atoms are stronger The forces between iodine molecules are stronger () (b) Predict the boiling point of bromine.... () Page of 34

2 (c) A redox reaction takes place when aqueous chlorine is added to potassium iodide solution. The equation for this reaction is: Cl 2 (aq) + 2KI(aq) I 2 (aq) + 2KCl(aq) Look at table above. What is the colour of the final solution in this reaction? Tick one box. Brown Orange Pale green Colourless () (d) What is the ionic equation for the reaction of chlorine with potassium iodide? Tick one box. Cl 2 + 2K 2KCl 2I + Cl 2 I 2 + 2Cl I + Cl I + Cl I + K + KI () (e) Why does potassium iodide solution conduct electricity? Tick one box. It contains a metal It contains electrons which can move It contains ions which can move It contains water () Page 2 of 34

3 (f) What are the products of electrolysing potassium iodide solution? Tick one box. Product at cathode hydrogen Product at anode iodine hydrogen oxygen potassium iodine potassium oxygen () (Total 6 marks) Q2. Sodium chloride is a raw material. (a) The electronic structure of a sodium atom is shown below. Complete the diagram for the electronic structure of a chlorine atom. A chlorine atom has 7 electrons. () (b) When sodium and chlorine react to form sodium chloride they form sodium ions (Na + ) and chloride ions (Cl ). How does a sodium atom change into a sodium ion? (2) Page 3 of 34

4 (c) The diagram shows apparatus used in a school laboratory for the electrolysis of sodium chloride solution. The solution contains sodium ions (Na + ), chloride ions (Cl ), hydrogen ions (H + ) and hydroxide ions (OH ). (i) Why do chloride ions move to the positive electrode? () Name the gas formed at the negative electrode. () (d) Chlorine and chlorine compounds are used to bleach wood pulp that is used to make paper. The article below is from a newspaper. Local people have been protesting outside a paper factory. They say: We want the company to stop using chlorine compounds. Chlorine compounds release poisons into the environment. The company should use safer compounds. The company replied: Chlorine has been used safely for many years to treat drinking water. Only tiny amounts of chlorine are released, which cause no harm. Using other compounds will be more expensive and may put us out of business. (i) Why are some local people worried about the use of chlorine compounds? () Why might other local people want the company to continue to use chlorine compounds? () Page 4 of 34

5 (iii) It is decided to have an inquiry. Why should this be done by independent scientists? () (Total 8 marks) Q3. Read the information in the box. Flash powder is used to produce special effects at pop concerts. Flash powder contains aluminium. The powder burns with a bright white flame and gives out lots of heat and light. It also produces white smoke. The flash powder is placed on stage in a special container. At the bottom of the container there is a thin piece of wire. When the flash is needed, electricity is passed through the wire. The wire gets hot and starts the aluminium burning. By russelljsmith [CC BY 2.0], via Flickr (a) When aluminium burns the reaction is exothermic. What is the meaning of exothermic? () (b) The hot wire provides energy to start the aluminium burning. What is the name given to the heat energy needed to start a chemical reaction?... energy () Page 5 of 34

6 (c) The white smoke produced is aluminium oxide. Aluminium oxide contains aluminium ions (Al 3+ ) and oxide ions (O 2 ). (i) Complete the diagram to show the electronic structure of an oxide ion. The atomic number of oxygen = 8 Use crosses (x) to represent the electrons. () The bonding in aluminium oxide is ionic. What causes the aluminium ions and oxide ions to be held together strongly? () (Total 4 marks) Page 6 of 34

7 Q4. Lead compounds have been used for thousands of years as colours in paint. Johannes Vermeer [Public domain], via Wikimedia Commons (a) A sample of a red oxide used in paint was found to contain 6.2 g of lead and 0.64 g of oxygen. Calculate the empirical (simplest) formula of this compound. You must show all your working to gain full marks. Relative atomic masses: O = 6; Pb = (4) Page 7 of 34

8 (b) A problem with lead compounds is that they slowly react with hydrogen sulfide in the air. This produces lead sulfide which is black. (i) Hydrogen sulfide has the formula H 2 S. The bonding in a molecule of hydrogen sulfide can be represented as: H S H Complete the diagram below to show the arrangement of the outer electrons of the hydrogen and sulfur atoms in hydrogen sulfide. Use dots ( ) and crosses (x) to represent the electrons. You need only show the outer shell electrons. (Atomic numbers: H = ; S = 6.) () Hydrogen sulfide has a low boiling point. Explain why. (2) (iii) Lead white is also used in paint. The white colour slowly darkens when lead sulfide is produced. The painting can be restored with hydrogen peroxide. This converts the black lead sulfide into white lead sulfate. Balance the equation for the reaction between lead sulfide and hydrogen peroxide (H 2 O 2 ). PbS (s) +...H 2 O 2 (aq) PbSO 4 (s) + 4H 2 O(l) () (Total 8 marks) Page 8 of 34

9 Q5. The picture shows a copper kettle being heated on a camping stove. Copper is a good material for making a kettle because: it has a high melting point it is a very good conductor of heat. (a) Explain why copper, like many other metals, has a high melting point. Your answer should describe the structure and bonding of a metal (4) Page 9 of 34

10 (b) Aeroplanes contain many miles of electrical wiring made from copper. This adds to the mass of the aeroplane. It has been suggested that the electrical wiring made from copper could be replaced by carbon nanotubes which are less dense than copper. The diagram shows the structure of a carbon nanotube. (i) What does the term nano tell you about the carbon nanotubes? () Like graphite, each carbon atom in the carbon nanotube is joined to three other carbon atoms. Explain why the carbon nanotube can conduct electricity. (2) (Total 7 marks) Page 0 of 34

11 Q6. The diagram represents a magnesium atom. (a) Use words from the box to answer these questions. electron neutron nucleus proton (i) What is the name of the central part of the atom?... What is the name of the particle with no charge?... (iii) What is the name of the particle with a negative charge?... () () () (b) Use the diagram above to help you answer these questions. (i) Draw a ring around the atomic (proton) number of this magnesium atom () Draw a ring around the mass number of this magnesium atom () Page of 34

12 (c) The diagram shows how magnesium and iodine atoms form magnesium iodide. Only the outer electrons are shown. The dots ( ) and crosses ( ) are used to represent electrons. Use the diagram to help you to answer this question. Describe, as fully as you can, what happens when magnesium reacts with iodine to make magnesium iodide. To gain full marks you should use the words atom, electron and ion in your answer (4) (Total 9 marks) Page 2 of 34

13 Q7. This question is about atoms and molecules. (a) Complete the table to show the relative masses of the particles in atoms. Name of particle Relative mass Proton... Neutron Electron... (2) (b) The diagram shows an oxygen atom. Use the correct number to complete each sentence The atomic (proton) number of the oxygen atom shown above is.... The mass number of the oxygen atom shown above is.... (2) (c) (i) Draw a ring around the correct answer to complete each sentence. isotopes. Oxygen atoms with different numbers of neutrons are called molecules. polymers. () An oxygen atom with a different number of neutrons has 0 neutrons. Draw a ring around the symbol which represents this atom. () Page 3 of 34

14 (d) A water molecule contains hydrogen and oxygen atoms. (i) Use the correct answer to complete the sentence. a compound an element a mixture Water is.... () Draw a ring around the correct structure of a water molecule. H O H O H H O H O () (iii) Draw a ring around the type of bonding in a water molecule. covalent ionic metallic () (iv) Draw a ring around the correct answer to complete each sentence. gaining The bonds in a water molecule are formed by losing electrons. sharing () (Total 0 marks) Q8. (a) Figure shows an atom of element G. Figure Draw a ring around the correct answer to complete each sentence. (i) Label A shows an electron an ion a nucleus () The particle labelled B is an isotope a molecule a neutron () Page 4 of 34

15 (iii) The mass number of element G is 5 6 () (iv) Use the periodic table to identify element G. Element G is boron carbon sodium () (b) Figure 2 shows a compound of G and hydrogen. Figure 2 Draw a ring around the correct answer to complete each sentence. (i) The formula of the compound in Figure 2 is GH 3 G 3 H 3HG () The type of bonding shown in Figure 2 is covalent ionic metallic () (Total 6 marks) Page 5 of 34

16 Q9. This question is about magnesium. (a) (i) The electronic structure of a magnesium atom is shown below. Use the correct answer from the box to complete each sentence. electrons neutrons protons shells The nucleus contains protons and... The particles with the smallest relative mass that move around the nucleus are called... Atoms of magnesium are neutral because they contain the same number of electrons and... (3) A magnesium atom reacts to produce a magnesium ion. Which diagram shows a magnesium ion? Tick ( ) one box. () Page 6 of 34

17 (b) Magnesium and dilute hydrochloric acid react to produce magnesium chloride solution and hydrogen. Mg(s) + 2 HCl(aq) MgCl 2 (aq) + H 2 (g) (i) State two observations that could be made during the reaction (2) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate. Describe a method for making pure crystals of magnesium chloride from magnesium and dilute hydrochloric acid. In your method you should name the apparatus you will use. You do not need to mention safety. (6) (Total 2 marks) Page 7 of 34

18 Q0. This question is about atoms. Atoms contain electrons, neutrons and protons. (a) (i) Which of these particles has a positive charge? Tick ( ) one box. Electron Neutron Proton () Which of these particles does not have an electrical charge? Tick ( ) one box. Electron Neutron Proton () Page 8 of 34

19 (b) How are the elements in the periodic table arranged? Tick ( ) one box. In order of increasing atomic number In order of increasing mass number In order of increasing reactivity () (c) The diagram shows the arrangement of the electrons in an atom of fluorine. (i) How many protons are in an atom of fluorine? Tick ( ) one box () Page 9 of 34

20 The boiling point of fluorine is 88 C. What is the state of fluorine at room temperature? Tick ( ) one box. Solid Liquid Gas () (d) Fluorine reacts with copper to form an ionic compound. (i) Explain, in terms of electrons and electronic structure, what happens to a fluorine atom when it reacts with copper. Use Above Figure to help you to answer this question. (2) Describe a chemical test which would show that a solution contains copper(ii) ions. (2) (Total 9 marks) Page 20 of 34

21 Q. A student investigated the conductivity of different concentrations of sodium chloride solution. The student set the apparatus up as shown in Figure. Figure The student measured the conductivity of the pure water with a conductivity meter. The reading on the conductivity meter was zero. (a) The student: added sodium chloride solution one drop at a time stirred the solution recorded the reading on the conductivity meter. The student s results are shown in the table below. Number of drops of sodium chloride solution added Relative conductivity of solution Page 2 of 34

22 (i) The student plotted the results on the grid shown in Figure 2. Plot the four remaining results. Draw a line of best fit, ignoring the anomalous result. Figure 2 Number of drops of sodium chloride added (3) One of the points is anomalous. Suggest one error that the student may have made to cause the anomalous result. () (iii) The student wanted to compare the conductivity of sodium chloride solution with the conductivity of potassium chloride solution. State one variable he should keep constant when measuring the conductivity of the two solutions. () Page 22 of 34

23 (b) (i) Explain, in terms of bonding, why pure water does not conduct electricity. (2) Explain why sodium chloride solution conducts electricity. (2) (iii) After he had added sodium chloride solution, the student noticed bubbles of gas at the negative electrode. Complete the sentence. The gas produced at the negative electrode is... () (Total 0 marks) Page 23 of 34

24 (d) 2 I + Cl 2 I Cl M. (a) The forces between iodine molecules are stronger (b) anything in range +30 to +20 (c) Brown (e) It contains ions which can move (f) hydrogen iodine [6] M2. (a) (b) accept dots / crosses / e must be drawn on diagram electrons do not need to be paired ignore brackets or + or -charges ignore 2,8,7 (one) electron recognition that electrons are involved lost / given away / transferred from sodium / transferred to chlorine owtte must be linked to electrons accept loses electron(s) for 2 marks NB loses 2 or more electrons gains mark reference to sharing / covalent max mark ignore charges on ions formed Page 24 of 34

25 (c) (i) any one from: ions / atoms / they are / it is negatively charged / anions accept they are negative opposite (charges) attract accept they are attracted or it is oppositely charged ignore opposite forces attract hydrogen accept H 2 ignore H or H + (d) (i) poisons released into environment (owtte) accept any sensible idea of harm / harmful / poisons / poisonous / pollution / damaging do not accept answers such as global warming / ozone layer etc. ignore safety unless qualified any one sensible idea eg loss of work / unemployment eg shops / house prices etc. or company goes out of business any adverse effect on local economy (owtte) any adverse effect on paper production / cost of paper / cost of water (treatment) allow less expensive to use chlorine or converse chlorine (compounds) have been used (for many years) without causing harm owtte only a tiny amount of chlorine is released so it would not cause harm ignore uses of chlorine to treat drinking water unless qualified (iii) ideas related to bias accept more reliable or valid or fair ignore more accurate / fair test [8] Page 25 of 34

26 M3. (a) gives out heat / energy or allow more energy given out in making bonds than is used in breaking bonds energy / heat transferred to surroundings ignore light (b) activation allow phonetic spelling (c) (i) 2 crosses on inner circle and 8 crosses on outer circle accepts dots / e / for electrons opposite charges (attract) allow electrostatic forces (attract) do not accept intermolecular attraction / shared electrons [4] M4. (a) mark for dividing mass by A r max 2 if A r divided by mass = 0.03 = 0.04 mark for correct proportions 3 4 mark for correct whole number ratio (allow multiples) can be awarded from correct formula Pb 3 O 4 mark for correct formula ecf allowed from step 2 to step 3 and step 3 to step 4 if sensible attempt at step correct formula with no working gains 2 marks Page 26 of 34

27 (b) (i) allow all dots or all crosses or e or e ignore inner shells and any inner electrons allow 4 non-bonded electrons anywhere on shell as long as not in overlap need not be paired forces of attraction / bonds between molecules are weak (owtte) do not accept intramolecular forces / covalent bonds are weak do not accept reference to ions or intermolecular forces / bonds are weak (owtte) or it is made of small molecules with weak forces of attraction if 2 marks not awarded made of small molecules / simple molecular gains mark forces of attraction are weak (without specifying between molecules / intermolecular) gains mark (accept easily broken / not much energy needed to break instead of weak) bonds are weak without specifying intermolecular would not gain a mark and would be ignored 2 (iii) 4 [8] M5. (a) reference to incorrect bonding or incorrect structure or incorrect particles = max 3 giant structure / lattice ignore many bonds made up of positive ions surrounded by delocalized / free electrons allow positive ions surrounded by a sea of electons with strong bonds / attractions allow hard to break for strong Page 27 of 34

28 so a lot of energy is needed to break these bonds / attractions / forces ignore high temperature ignore heat (b) (i) that they are very small or -00 nanometres or a few(hundred) atoms accept tiny / really small / a lot smaller / any indication of very small eg. microscopic, smaller than the eye can see ignore incorrect numerical values if very small is given delocalised / free electrons allow sea of electrons one non-bonded electron from each atom accept electron(s) moving through the structure / nanotube allow electron(s) carry / form / pass current / charge [7] M6. (a) (i) nucleus neutron (iii) electron (b) (i) 2 24 Page 28 of 34

29 (c) any four from: sharing / covalent / metallic = max 3 magnesium (atom) reacts with two iodine (atoms) magnesium (atom) loses electrons 2 electrons (from each atom) Iodine (atom) gains electron(s) electron or an electron (to each atom) iodide ion formed allow iodine ion iodide has negative charge / is a negative ion / particle allow iodine ignore I 2 magnesium ion formed magnesium has positive charge oppositely charged ions attract a giant structure / lattice is formed allow mark for unqualified reference to ion formation or ionic bonding 4 [9] M7. (a) proton ignore ± electron very small owtte allow zero allow values from / 800 to / 2000 or (b) 8 6 (c) (i) Isotopes (d) (i) compound Page 29 of 34

30 H-O-H (iii) covalent (iv) sharing [0] M8. (a) (i) an electron a neutron (iii) (iv) boron (b) (i) GH 3 covalent [6] M9. (a) (i) neutrons this order only electrons protons box on the left ticked (b) (i) effervescence / bubbling / fizzing / bubbles of gas do not accept just gas alone magnesium gets smaller / disappears allow magnesium dissolves allow gets hotter or steam produced ignore references to magnesium moving and floating / sinking and incorrectly named gases. Page 30 of 34

31 Marks awarded for this answer will be determined by the Quality of Communication (QC) as well as the standard of the scientific response. Examiners should also refer to the information in the Marking Guidance and apply a best fit approach to the marking. 0 marks No relevant content Level ( 2 marks) There are simple statements of some of the steps in a procedure for obtaining magnesium chloride. Level 2 (3 4 marks) There is a description of a laboratory procedure for obtaining magnesium chloride from dilute hydrochloric acid and magnesium. The answer must include a way of ensuring the hydrochloric acid is fully reacted or a method of obtaining magnesium chloride crystals. Level 3 (5 6 marks) There is a well organised description of a laboratory procedure for obtaining magnesium chloride that can be followed by another person. The answer must include a way of ensuring the hydrochloric acid is fully reacted and a method of obtaining magnesium chloride crystals. examples of the points made in the response: hydrochloric acid in beaker (or similar) add small pieces of magnesium ribbon until magnesium is in excess or until no more effervescence occurs * filter using filter paper and funnel filter excess magnesium pour solution into evaporating basin / dish heat using Bunsen burner leave to crystallise / leave for water to evaporate / boil off water decant solution pat dry (using filter paper). *Student may choose to use a named indicator until it turns a neutral colour, record the number of pieces of magnesium added then repeat without the indicator. 6 [2] M0. (a) (i) Proton Neutron (b) In order of increasing atomic number (c) (i) 9 Gas Page 3 of 34

32 (d) (i) gains (one) electron (to gain a) full outer energy level or noble gas configuration allow because it has seven outer electrons add sodium hydroxide (solution) allow ammonia (solution) or ammonium hydroxide or any other soluble hydroxide or flame test (forms a) blue precipitate second mark dependent on suitable reagent being added allow blue green / blue / green if flame test given [9] M. (a) (i) points correctly plotted ( ± ½ small square) four points = 2 marks three points = mark Max 2 straight line of best fit using full range of points from 0,0 any one from: must explain why the point is below the line the solution may not have been properly stirred the electrodes may have been a larger distance apart the drop of sodium chloride may have been a smaller volume / smaller allow not enough sodium chloride added allow smaller amount of sodium chloride do not allow too few drops added ignore the student may have misread the conductivity meter (iii) any one from: the volume of pure water allow amount the concentration (of the solutions added) the volume (of the drops) of solution added ignore number of drops the distance between the electrodes the same electrodes or electrodes made of the same material same depth or surface area of electrodes in the water constant power supply ignore current stirred (b) (i) because (pure) water is covalent / molecular (simple) or contains molecules Page 32 of 34

33 therefore (pure) water has no free / mobile electrons or ions molecules do not have a charge or molecules do not contain ions gains 2 marks because there are ions in sodium chloride allow Na + and / or Cl (ions) or ionic bonding. Ignore particles other than ions for MP. which can move or carry the current / charge MP2 must be linked to ions only. (iii) Hydrogen allow H 2 / H [0] Page 33 of 34

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