Worksheet on Elements, Compounds and Mixtures Name : ( ) Date: 05042007 Class : Instruction: Answer all questions 1-9 below by filling the correct answer in the given bracket. 1. How many atoms are present in one molecule of sulphurous acid, H 2 SO 3? A 3 B 5 C 6 D 8 ( ) 2. A mixture. A has a fixed melting point. B has a fixed boiling point. C is made by a chemical reaction. D can be separated by physical methods. ( ) 3. Which pair of substances are both mixtures? A air; sea water B diamond; vinegar C ethanol; lime water D water; air ( ) 4. Which picture shows a compound made of two elements. ( ) 5. Which element conducts electricity at r.t.p.? A Bromine. B Nitrogen. C Sulphur. D Sodium. ( ) 6. Which one of the following sets contains only one metal? A sodium hydrogen calcium B iron oxygen sulphur C copper carbon calcium D sulphur magnesium copper ( ) 7. Which one of the following is an element? A Salt B Water C Air D Chlorine ( )
8 The structural formula of glycerol is Which statement about glycerol is not true? A Its molecular formula is C 3 H 8 O 3. B It contains three elements. C One molecule contains a total of 14 atoms. D Its molecular formula and empirical formula are different. ( ) 9. Which diagrams correctly show the molecules in ammonia, nitrogen and hydrogen? A ammonia nitrogen hydrogen B C D ( )
Instruction: Questions 10-17 are structured questions. Fill your answers in the blank spaces provided 10. Choose your answers from the following list of substances. air calcium carbon dioxide chlorine gold hydrogen ice nitrogen sea water sugar (a) Name four elements. (b) Name two substances that are mixtures. (c) Name two substances that are single compounds. (d) Name one solid compound that contains the element carbon. 11(a) The formula of one molecule of nitric acid is HNO 3. (i) Name the elements present in nitric acid. What is the total number of atoms in one molecule of nitric acid? 12. Fructose is a sugar used in food. The structural formula of one form of fructose is given below.
(i) What are the elements present in fructose? What is the molecular formula of fructose? (iii) What is the empirical formula of fructose? 13. A list of substances is given below. Air Water Ethanol Steel Chromium Graphite Petrol Nylon Protein Choose from the list one substance which (i) is an element. is a compound containing two elements only. (iii) is a compound containing nitrogen. (iv) is a mixture of compounds. (v) is a mixture of elements. 14(a) Substances can be classified as elements, compounds or mixtures. Put each of the following into one of these classes. (i) Air. Ammonia. (iii) Ethanol.
(iv) Iodine. (b) Mixtures of metals (e.g. brass) are commonly called : 15. The properties of some metal oxides are given in the table. All the oxides are solid at room conditions. name of oxide formula of colour effect of heating the oxide oxide copper(i) oxide Cu 2 O red remains red lead(iv) oxide PbO 2 brown oxygen produced; solid turns yellow mercury(ii) oxide HgO red oxygen produced; silvery liquid produced potassium peroxide K 2 O 2 white remains white Zinc oxide ZnO white solid turns yellow when hot and becomes white again on cooling (a) Which of these oxides do not undergo a chemical reaction when heated?... [2] (b) Suggest the identity of the silvery liquid formed from mercury(ii) oxide.... 16 (a) State three differences in the properties of elements that are metals and elements that are non-metals. Write your answer in the table below. 1 2 3 Property Metals Non-metals (b) Anhydrite is a white rock with the formula CaSO 4. Name the elements present in anhydrite and state whether each one is a metal or a non-metal.
17. Fig. B shows some of the molecules in the air above an active volcano. For example, a water molecule has the formula H 2 O and is shown by in the diagram. Write the formulas for the other molecules in the air above the volcano.. Fig B 18. Use examples :a mixture of iron filings and sulphur, a compound iron(ii) sulphide to illustrate the differences of properties between a mixture and a single compound. [4] http://www.docstoc.com/docs/2787175/worksheet-on-elements-compounds-and- Mixtures