Physical Properties of Metals:
Hardness: Most
of the metals are hard, except alkali metals, such as sodium,
potassium, lithium, etc. Sodium, potassium, lithium etc. are very soft
metals, these can be cut using knife.
Strength: Most
of the metals are strong and have high tensile strength. Because of
this big structures are made using metals, such as copper and iron.
State: Metals are solid at room temperature except mercury.
Sound: Metals
produce ringing sound, so, metals are called sonorous. Sound of metals
is also known as metallic sound. This is the cause that metal wires are
used in making musical instruments.
Conduction: Metals
are good conductor of heat and electricity. This is the cause that
electric wires are made of metals like copper and aluminium.
Malleability: Metals
are malleable. This means metals can be beaten into thin sheet. Because
of this property iron is used in making big ships.
Ductility: Metals are ductile. This means metals can be drawn into thin wire. Because of this property wires are made of metals.
Melting and boiling point: Metals have generally high melting and boiling points.
Density: Most of the metals have high density.
Color: Most of the metals are grey in color. But gold and copper are exceptions.
Chemical Properties of Metals
Reaction with oxygen:
Most of the metals form respective metal oxides when react with oxygen.
Examples:
Reaction of potassium with oxygen: Potassium metal forms potassium oxide when reacts with oxygen.
Reaction of sodium with oxygen: Sodium metal forms sodium oxide when reacts with oxygen.
Lithium, potassium, sodium, etc. are known as alkali metals. Alkali metals react vigorously with oxygen.
Reaction of magnesium metal with oxygen: Magnesium
metal gives magnesium oxide when reacts with oxygen. Magnesium burnt
with dazzling light in air and produces lot of heat.
Reaction of aluminium metal with oxygen: Aliminium metal does not react with oxygen at room temperature but it gives aluminium oxide when burnt in air.
Reaction of zinc metal with oxygen: Zinc does not react with oxygen at room temperature. But it gives zinc oxide when heated strongly in air.
Reaction of Iron metal with oxygen: Iron does not react with oxygen at room temperature. But when iron is heated strongly in air, it gives iron oxide.
Iron fillings give sparkle in flame when burnt.
Reaction of copper metal with oxygen: Copper does not react with oxygen at room temperature but when burnt in air, it gives copper oxide.
Reaction of metals with water:
Metals form respective metal hydroxide and hydrogen gas when react with water.
Most of the metals do not react with water. However, alkali metals react vigorously with water.
Reaction of sodium metal with water: Sodium metal forms sodium hydroxide and liberates hydrogen gas along with lot of heat when reacts with water.
Reaction of potassium metal with water: Potassium metal forms potassium hydroxide and liberates hydrogen gas along with lot of heat when reacts with water.
| 1. Caesium is a metal that is more reactive than aluminium. Which reaction would produce caesium? a. electrolysing aqueous caesium chloride b. electrolysing molten caesium chloride c. heating caesium carbonate d. heating caesium oxide with carbon 2. Which of the following processes does not result in the formation of both carbon dioxide and water? a. addition of a dilute acid to a carbonate b. burning ethanol c. burning methane d. heating crystals of hydrated sodium carbonate 3. Which element is always present with iron in mild steel? a. aluminium b. carbon c. chromium d. nickel 4. Hydrogen gas will reduce a. calcium oxide b. silver oxide c. magnesium oxide d. potassium oxide 5. Which oxide can be reduced to the metal using carbon a. calcium oxide b. magnesium oxide c. sodium oxide d. zinc oxide 6. Which substance removes impurities from iron ore in the blast furnace? a. carbon b. limestone c. sand d. slag 7. An excess of iron filings is added to a solution containing a mixture of the ions Mg2+, Ca2+, Cu2+and Ag+. Which 2 metals will be displaced from this solution? a. calcium and copper b. calcium and magnesium c. copper and silver d. magnesium and silver 8. What reacts with hydrochloric acid to give hydrogen? a. ammonia b. iron c. silver d. sodium hydroxide 9. Why does the color of aqueous potassium bromide change when chlorine gas is bubbled into it? a. a compound is formed between chlorine and bromine b. a solution of potassium chloride is formed c. the chlorine oxidises bromide ions to bromine d. the potassium bromide is reduced 10. Which carbonate decomposes on heating to give a black solid and a colourless gas? a. calcium carbonate b. copper(II) carbonate c. sodium carbonate d. zinc carbonate 11. Which substance is not an essential raw material in the extraction of iron in a blast furnace? a. air b. coke c. limestone d. sand 12. Which element reacts with oxygen to form a compound that is a gas at room temperature? a. magnesium b. hydrogen c. copper d. carbon 13. Caesium is a metal that is more reactive than aluminium. Which reaction would produce caesium? a. electrolysing aqueous caesium chloride b. electrolysing molten caesium chloride c. heating caesium carbonate d. heating caesium oxide with carbon 14. What is a disadvantage of recycling metals? a. collection and transportation costs money b. metal ores are a finite resource c. most metals corrode slowly in the environment d. scrap metal melts when heated 15. Which of the following processes does not result in the formation of both carbon dioxide and water? a. addition of a dilute acid to a carbonate b. burning ethanol c. burning methane d. heating crystals of hydrated sodium carbonate 16. Hydrogen gas will reduce a. calcium oxide b. silver oxide c. magnesium oxide d. potassium oxide 17. Which element is always present with iron in mild steel? a. aluminium b carbon c. chromium d. nickel 18. Which oxide can be reduced to the metal using carbon? a. calcium oxide b. magnesium oxide c. sodium oxide d. zinc oxide 19. Which substance removes impurities from iron ore in the blast furnace? a. carbon b. limestone c. sand d. slag 20. What reacts with hydrochloric acid to give hydrogen? a. ammonia b. iron c. silver d. sodium hydroxide 21. Which carbonate decomposes on heating to give a black solid and a colorless gas? a. calcium carbonate b. copper(II) carbonate c. sodium carbonate d. zinc carbonate 22. Which substance is not an essential raw material in the extraction of iron in a blast furnace? a. air b. coke c. limestone d. sand 23. Which element reacts with oxygen to form a compound that is a gas at room temperature? a. magnesium b. hydrogen c. copper d. carbon 24. A sample of air is slowly passed through aqueous sodium hydroxide and then over heated copper. Which gases are removed by this process? a. carbon dioxide and water vapour b. carbon dioxide and oxygen c. nitrogen and oxygen d. nitrogen and water vapour 25. When heated, solid X gives off a gas which turns limewater milky. The residue reacts with dilute acid and also with aqueous alkali. What is X? a. copper(II) carbonate b. magnesium carbonate c. sodium carbonate d. zinc carbonate 26. An element is burned in an excess of oxygen. Which statement about the oxide formed is always correct? a. it is a crystalline solid b. it is greater in mass than the element c. it is soluble in water d. it is white in color 27. Which substance can be reduced by carbon? a. aluminium oxide b. calcium carbonate c. iron(III) oxide d. magnesium oxide 28. Which of the following is a typical property of transition metals? a. they form colored compounds b. they have low densities c. they have low melting points d. they react with cold water to give hydrogen 29. What happens when zinc is placed in aqueous copper(II) sulphate? a. copper atoms are oxidised b. zinc atoms are oxidised c. copper ions are oxidised d. zinc ions are oxidised 30. Which substance does not need air as a raw material for its manufacture? a. ammonia b. iron c. sodium d. sulphuric acid 31. Which of the following is not a use of silicon or its compounds? a. making fire-resistant plastics b. making glass c. making polishes d. making smokeless fuel 32. Compound X reacts with some metals to liberate hydrogen and is used to make fertilisers. It gives a white precipitate when added to aqueous barium nitrate. What is X? a. ammonium sulphate b. hydrochloric acid c. potassium nitrate d. sulphuric acid 33. Which industrial process uses iron as a catalyst? a. making ammonia from nitrogen and hydrogen b. making ethanol from ethene and steam c. making steel d. making sulphur trioxide from sulphur dioxide and oxygen 34. Which pair of elements will combine to form an ionic compound? a. carbon and chlorine b. fluorine and sodium c. hydrogen and oxygen d. oxygen and carbon 35. How does the mass of a sample of copper(II) oxide change when it is heated in hydrogen and in oxygen?
36. Sodium is a metal. Using only this information, what can be deduced about sodium? a. it has a low melting point b. it is a conductor of electricity c. it is less dense than water d. it is very reactive 37. Which substance reacts with water to form a soluble compound and an insoluble gas? a. ammonium sulfate b. caesium c. calcium carbonate copper 38. Which compound does not give off a gas when heated? a. hydrated copper(II) sulfate b. hydrate sodium carbonate c. magnesium carbonate d. sodium carbonate 39. Which metal should be used in the sacrificial protection of the hull of a boat made from iron? a. calcium b. copper c. lead d. zinc 40. A coil of clean copper wire is suspended in a beaker of aqueous silver nitrate. Crystals of silver are deposited on the copper wire. Which statement is not correct? a. the copper is oxidised b. the solution turns blue c. the total mass of the crystals of silver increases gradually d. the total number of positive ions in the solution is unchanged 41. In the manufacture of iron by the blast furnace, which are the main gases that escape from the top of the blast furnace? a. carbon monoxide, carbon dioxide, hydrogen b. nitrogen, carbon dioxide, carbon monoxide c. nitrogen, oxygen, steam d. oxygen, carbon dioxide, sulfur dioxide 42. When heated, solid X gives off a gas. When this gas is bubbled through limewater, a white precipitate is formed. The residue after heating solid X reacts with dilute acid and also with aqueous alkali. What is X? a. copper(II) carbonate b. magnesium carbonate c. sodium carbonate d. zinc carbonate 43. The information below concerns 3 elements X, Y, and Z. X: Its oxide is decomposed by heat to the element. Y: Its carbonate is not decomposed by heat. Z: Its oxide is not decomposed by heat but its carbonate decomposes. In order of decreasing reactivity, the 3 elements should be arranged as: a. Y Z X b. X Y Z c. Y X Z d. X Z Y Answers1. b2. d 3. b 4. b 5. d 6. b 7. c 8. b 9. c 10. b 11. d 12. d 13. b 14. a 15. d 16. b 17. b 18. d 19. b 20. b 21. b 22. d 23. d 24. b 25. d 26. b 27. c 28. a 29. b 30. c (sodium is obtained through electrolysis) 31. d 32. d 33. a 34. b 35. b 36. b 37. b 38. c 39. d 40. b 41. b 42. d 43. a Structured Questions and Worked Solutions1a. Under what conditions does water react with i. sodium ii. magnesiumIn each case, name the products formed. b. Water supplies are obtained from rivers, boreholes and reservoirs. The water must be treated before use. Describe and explain the two main processes in the purification of water supplies. c. Water supplies that have passed through iron pipes contain iron(II) ions, Fe2+ and iron(III) ions, Fe3+. In the presence of air, iron(II) ions are slowly changes to iron(III) ions. Construct the equation for the reaction between iron(II) ions, hydrogen ions, H+, and oxygen to form iron(III) ions and water. Solution 1ai. In cold water. Products: sodium hydroxide and hydrogen 1aii. Heated with steam. Products: magnesium oxide and hydrogen 1bi. filtration: solid particles are removed. 1bii. chlorination: germs and bacteria are killed by sterilising water with chlorine. 1c. 4Fe2+ (aq) + O2 (g) + 4H+ (aq) ---> 4Fe3+ (aq) + 2H2O (l) 2. Calcium oxide is produced by heating a mixture of limestone and coke in a lime kiln. CaCO3 <---> CaO + CO2 ai. Explain the meaning of the symbol <---> aii. In the lime kiln, the carbon dioxide is allowed to escape. Why does this increase the yield of calcium oxide? b. The calcium oxide reacts with water to form slaked lime. i. Give the equation for this reaction ii. State a use of slaked lime Solution 2ai. It shows that the decomposition of calcium oxide in the lime kiln is a reversible reaction. 2aii. The decrease in carbon dioxide concentration causes the equilibrium to shift to the right to produce more carbon dioxide to replace those that escaped. Therefore, more calcium carbonate decomposes to give calcium oxide. 2bi. CaO + H2O --> Ca(OH)2 2bii. It is used to treat acidic soils. It reacts with acid to produce salt and water. 3. Choose from the following metals to answer the questions below.
Each metal can be used once, more than once, or not at all. Name a metal which a. is manufactured by the electrolysis of its molten oxide b. has a variable valency c. is used to galvanise iron d. has a carbonate which is coloured e. is alloyed with zinc to make brass Solution 3a. aluminim 3b. copper/iron 3c. zinc 3d. copper 3e. copper 4. In separate experiments, powdered samples of metal X and metal Y reacted with solutions of nickel(II) sulphate and of iron(II) sulphate. The following table shows how the colours of the solutions changed.
a. predict the order of reactivity for the four metals X, Y, nickel, and iron. b. Metal Y was placed in aqueous copper(II) sulphate. i. What colour change was seen? ii. Give one other observation c. Write the ionic equation, with state symbols, for the reaction between iron and aqueous nickel(II) sulphate. Solution a. from least reactive to most reactive: nickel, metal X, iron, metal Y bi. blue copper(II) sulphate solution decolourises bii. a reddish brown deposit is formed c. Fe (s) + Ni2+ (aq) ----> Fe2+ (aq) + Ni (s) |
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