ELEMENTS, COMPOUNDS AND MIXTURES December, 11 th 2 marks 1. a) The list below contains three elements and three compounds. Say which are elements and which are compounds. Iodine (I 2 ) Water (H 2 O) Fluorine (F 2 ) Sulphuric acid (H 2 SO 4 ) Carbon dioxide (CO 2 ) Sulphur (S) b) The fertiliser a farmer uses is based on ammonium nitrate (NH 4 NO 3 ). Is this substance an element or a compound? Explain your answer. (fertiliser= fertilizante; farmer = granxeiro) 2. Four test tubes contain different substances as shown in the diagram 4 marks 3 marks a) I would use filtration to separate the substances in tube. b) I would use simple dissolving to separate the substances in tube.. c) I would use evaporation to separate the substances in tube. d) I would use distillation to separate the substances in tube. 3. Choose from the list the most suitable method for each of the following separations: a) To separate the mixture of sand and salt (sand= area; salt= sal) b) To obtain some solid salt from a solution of salt in water c) To obtain a sample of clean water from some muddy water (clean water= auga limpa ; muddy water = auga turbia) chromatography dissolving distillation evaporation filtration fractional distillation 4 marks 4. When 2 liquids don t mix, they are called inmiscible. The liquids can be separated in a separating funnel. (funnel= funil) Draw the funnel, containing oil and water. How do you separate the two liquids?. 5 marks 5. The figure shows laboratory apparatus which can be used to produce almost pure alcohol from a mixture of alcohol and water. a. Name the process being used. b. Name the parts of the apparatus. c. What will be left in the flask at the end of the process? 10 marks 6. Describe how you could separate and collect the first substance from each mixture. a) salt and sand b) iron filings and sugar (iron filings= limaduras de ferro) c) water and salt d) sand and sugar e) oil and water
12 marks 7. Choose the best option a) A heterogeneous mixture is poured through a piece of filter paper that is positioned over a beaker. What is the substance that is collected in the beaker? (poured= vertida; beaker= vaso de precipitados) A. heterogeneous mixture B. solid C. solution b) Imagine you were stranded on a desert island and you needed to get drinking water from muddy water. Which of the following techniques would you use? (to strand= perderse, estar desamparado) A. filtration B. evaporation C. diffusion c) When we open a bottle of perfume, particles of perfume spread out until they reach our nose and we are able to smell them. Which of the following best describes this movement of particles? (to spread out= esparcirse) A. boiling B. diffusion C. dissolving d) Which word best describes air? A. mixture B. compound C. element e) Which phrase best describes an element? A. it occurs naturally B. it is a metal C. it can t be split into simpler materials (to split= separarse) f) Which one of the following is not an example of a chemical change? i. rusting of iron (rusting= corrosion) iii. heating ice to form water ii. burning a piece of wood (burning= queimar) iv. frying an egg 10 marks 8. Look at the descriptions of processes below. In each case, type the word that best describes it. You can choose from the list at the bottom. Make sure you spell the word correctly. a) Pure steam is turned back into pure water... b) Solids are removed from a suspension of sand and rock in salt solution. c) Fresh water is separated from salty water by boiling it, collecting the steam and letting it turn back into water... d) Salt is recovered from salt solution by heating the water so it disappears. e) Solid salt is removed from rock salt forming a solution in water
1. CLICK [A-D] for the best option: 5 1 Which two words apply to the substance nitrogen (N 2 )? molecule? What is the formula of the 50 marks liquid, compound 2 Which picture represents a mixture of molecules of two elements? C 6 H 2 O C 3 H 6 C 2 H 6 O 2C 6 HO 6 Which two words apply to the substance air? liquid, mixture solid, element liquid, element gas, mixture 3 Which word means the 'smallest particle of a substance'? 7 Given the STATEMENT about..., decide whether it is TRUE or FALSE for an ELEMENT, COMPOUND or MIXTURE STATEMENT about... has a fixed melting point? ELEMENT COMPOUND MIXTURE true or false? true or false? true or false? formula symbol molecule 8 Which picture represents a mixture of atoms of an element and molecules of another element? atom 4 Which of the following reactions involves the chemical change... two compounds two compounds? carbon dioxide + calcium hydroxide calcium carbonate + water zinc + sulphur zinc sulphide water hydrogen + oxygen oxygen + copper sulphide copper sulphate
9 About the periodic table. Which statement is TRUE? 14 Which of these is an element? most elements are nonmetals there are about 1000 different elements in the Periodic Table most metals are nonmagnetic there are no liquid elements at room temperature and pressure 15 alcohol Bromine (Br 2 ) magnesium oxide (MgO) Water (H 2 O) 10 Which statement is TRUE about the Periodic Table of Elements? metals are mostly in the middle and on the right there are about 500 different elements about 1/4 of the elements are metals all non-metals are on the right Which particle is a compound made up of three elements? 2 8 7 4 16 Which picture represents a mixture of two compound molecules? 11 Which of these is a compound? P 4 Co F 2 MgO 12 Which two words apply to the substance wood? solid, compound 13 Which two words apply to the substance CuSO 4 solid, compound 17 Which of the following is the chemical symbol for the element nitrogen? [8e-70] Ne N Ni No
18 Which picture represents molecules of a pure element? 20 The best way to determine whether a sample of a white solid is table sugar would be to: a) taste it b) determine its melting point c) weigh it d) dissolve it in water 21 A mixture must always: a) be heterogeneous c) contain two substances 19 Which picture represents a mixture of molecules of an element (diatomic) and molecules of a compound? d) have definite composition e) be homogeneous 22 Which of the following is always true when a substance undergoes a physical change? a) Its density remains the same. b) Its composition remains the same. c) It boils. d) A new substance is formed Here are pictures of some different particle arrangements. 23. Which of them are: - Pure elements - Elements made of SINGLE ATOMS - An element made of MOLECULES 24. Which of them are: - Mixture of TWO elements - Mixture of THREE elements 25. Which of them are: - PURE compounds - Mixture of TWO compounds