Half Yearly Exam 2015

Transcription

1 GOZO OLLEGE Secondary School KULLEĠĠ T GĦWDEX Skola Sekondarja Half Yearly Exam 015 Year 9 Track HEMISTRY Time: 1½ hours Name: lass: Useful Data: tomic numbers and relative atomic masses are given in the periodic table below. The Periodic Table Li 3 3 Na K Rb s 55 3 Fr 87 9 e 4 4 Mg 1 40 a 0 88 Sr a Sc 1 89 Y La Ti 91 Zr Hf 7 51 V 3 93 Nb Ta 73 5 r 4 55 Mn 5 96 Mo W 74 Key: Tc Re 75 1 H 1 56 Fe Ru Os 76 a X b 59 o Rh Ir Ni Pd Pt u g u Zn d Hg 80 relative atomic mass symbol atomic number l Ga In Tl Si Ge Sn Pb 8 14 N P 75 s 33 1 Sb i O 8 3 S Se Te Na Po F l r I Na t He 0 Ne r Kr Xe 54 Rn 86 Marks Grid [ For Examiner s use only ] Question Number Maximum Mark ctual Mark Section Section Theory Total Theory Paper: 85% Practical: 15% Final Score: 100% hemistry :: HY 015 :: Year 9 :: Track Page 1 of 8

2 Section : This section carries 60 marks. nswer all questions in this section. 1a. Label each process as a physical or chemical change: i) perfume evaporating on your skin ii) a bomb exploding iii) wood rotting iv) a piece of iron rusting v) melting copper metal 5 b. Name the following equipment: i) ii) iii) iv) v) 5 a. Write the chemical formula of the following substances: i) potassium oxide ii) sodium nitride iii) magnesium nitrate iv) iron(iii) chloride v) lead(ii) sulfate 5 hemistry :: HY 015 :: Year 9 :: Track Page of 8

3 b. Write the chemical name of the following substances: i) Kr ii) NH4l iii) Fel iv) l(so4)3 v) a(no) 5 3 onvert the following word equations into balanced chemical equations: a. hydrogen + oxygen water b. sodium + chlorine sodium chloride c. aluminium + oxygen aluminium oxide d. sodium + water sodium hydroxide + hydrogen e. calcium hydroxide + carbon dioxide calcium carbonate + water 4a. Fill in the missing gaps in this table: Symbol tomic no. Mass no. No. of protons No. of electrons 1 6 No. of neutrons O l Ne b. Write the electron configuration of the following: i) a sodium atom ii) a fluorine atom iii) a magnesium atom iv) a nitride ion 4 hemistry :: HY 015 :: Year 9 :: Track Page 3 of 8

4 5a Lithium fluoride (LiF) is an ionic substance. Draw a dot cross diagram to show the ions of this compound. 5 b. mmonia (NH3) is a covalent compound. Draw a dot cross diagram to show the bonding in this compound. 5 6 This question is about the kinetic theory of matter. Use your knowledge of this theory to explain the following statements: a. You can smell hot coffee from several metres away, yet you have to be near cold coffee to smell it. hemistry :: HY 015 :: Year 9 :: Track Page 4 of 8

5 b. Scientists calculate that gas particles can travel at speeds of up to 500 m/s. However when a person wearing a perfume enters a room, it takes several minutes for the smell to reach the back of the room. c. The following apparatus was set up. fter some time a white ring of smoke was observed. Give explanations for the following observations: i) It took a few minutes before for the white cloud to form. ii) The white cloud formed nearer to the cotton wool soaked in the hydrochloric acid. iii) Warming the concentrated ammonia solution and hydrochloric acid before carrying out the experiment would reduce the time taken for the white cloud to form. hemistry :: HY 015 :: Year 9 :: Track Page 5 of 8

6 Section : This section carries 40 marks. nswer any two questions from this section on the foolscaps provided. 7 Iron filings, sand and ammonium chloride were found mixed together in a beaker. student was given the task of separating the three substances from each other. a. Label the following diagram. D b. Describe what the student should do to separate the iron filings from the rest of the mixture. 3 c. The remaining mixture now contains sand and ammonium chloride. The student was told that ammonium chloride sublimes on heating. It decomposes into two gases, ammonia and hydrogen chloride. On cooling they reform ammonium chloride in the solid state. i) Is it true that ammonium chloride sublimes? 1 ii) What is the name given for what happens to ammonium chloride on 1 heating? iii) Describe the method to separate sand and ammonium chloride using heat only. 3 iv) Label the following diagram. D d. hromatography is another separating technique that chemists use. Ink is normally made of coloured liquids that are mixed together to obtain a particular shade of colour. hemistry :: HY 015 :: Year 9 :: Track Page 6 of 8

7 i) Describe how this technique is performed. 3 ii) Draw a labelled diagram of a chromatography setup. 3 iii) Why do the different coloured inks separate from each other on the chromatogram? 8 student was given a task to obtain salt (Nal) from a sample of rock salt. a. What are the two main components of rock salt? 1 b. State which substance is soluble and which is insoluble in water. c. What is the name of liquids that dissolve solid substances? 1 d. What is the name of a substance that dissolves in a liquid? 1 e. What is the name of the mixture that results when a substance dissolves in a 1 liquid? f. To separate the rock from the salt, water must be added to dissolve the salt from the insoluble rock. Describe the process that is required to separate the rock from the salt solution. 3 g. Label the following diagram which is used in the process above. 3 h. The remaining salt solution is still a mixture of salt and water. Describe the process which the student should do to obtain the salt in the solid state. 3 i. Label the following diagram which is used in the process above. j. It is normal for the salt in rock salt to be a mixture of salts. What should the student do to check whether the salt obtained is pure? 3 hemistry :: HY 015 :: Year 9 :: Track Page 7 of 8

8 9 Oil, water and ethanol are three liquids. Water and ethanol mix well together but they do not mix with oil. a. What are liquids that mix together called? 1 b. What are liquids that do not mix together called? 1 c. Describe what you would do to separate the oil from the rest of the liquids. 4 d. Label the following diagram that is used in the process above. 3 e. Oil stays on top of the mixture. Why do you think this happens? 1 f. Describe what you would do to separate the remaining water and ethanol. 6 g. Label the diagram below that is used in the process above. D 4 hemistry :: HY 015 :: Year 9 :: Track Page 8 of 8