2- Common Metals

CE : Section 2 Common Metals LQ P.1

CE : Section 2 Common Metals 1.

93 1(a) Aluminium and iron can be used in making window frames. (i) Describe an experiment to show that aluminium is more reactive than iron. (ii) Although aluminium is more reactive than iron, explain why most window frames are now made of anodized aluminium instead of painted iron. (5 marks)

2. 94 1 The table below lists some information about three metals X, Y and Z. Metal Atomic number

X 12

Action of cold water

No apparent change

Action of 0.1 M hydrochloric acid

Y 20 A colourless gas slowly evolves

A colourless gas evolves

---

Z ---No apparent change No apparent change

(a) To which group in the Periodic Table does Y belong ? (b) (i) Write an equation for the reaction between X and 0.1 M hydrochloric acid. (An ionic equation will NOT be accepted for this equation) (ii) Draw electronic structures for the TWO products formed in (i) above, showing electrons in the outermost shell ONLY. (c) What would be observed when Y is added to 0.1 M hydrochloric acid ? (d) Based on the results of the reactions given in the above table, arrange the three metals in descending order of reactivity. Explain your answer. (8 marks) 3. 95 6(b) The table below gives some information about five metals. Abundance in Metal

the earth crust (%) 8.1 0.0055 0.0000004 5.0 0.007

Al Cu Au Fe Zn

Price per kg ($)

Relative resistance of corrosion

Relative

(1 = least resistant, 4 =most

metal (1 = lowest, 3 =

resistant)

highest)

170 140 1100000 20 160

3 3 4 1 2

strength

of

1 3 2 3 2

(i) Although gold has a very low abundance in the earth's crust, gold was discovered by man a long time ago. Why ? (ii) Which of the metals in the above table is the most suitable to make pipes for hot water ? Explain your answer. (iii) (1) Aluminium does not corrode easily. Why ? (2) Aluminium is a principal material for making aircraft but its strength is relatively low. Suggest how the strength of aluminium can be improved to made it suitable for making aircraft. (iv) (1) Based on the information given in the table, suggest ONE factor that affects the price of a metal. (2) Suggest ONE other factor (not indicated in the table) that can also affect the price of a metal. (9 marks) 4. 96 4 Briefly describe an experiment, using the following apparatus and materials, to show that air is necessary for the rusting of iron. 2 test tubes, a test tube holder, a Bunsen burner, 2 clean iron nails, paraffin oil and tap water. (5 marks + 3) 5. 96 8(b)

CE : Section 2 Common Metals LQ P.2

The diagram below shows a ten dollar coin which is made of two alloys, X and Y.

(i) (1) What is an alloy? (2) State TWO properties of an alloy that make it suitable as a coinage metal. (ii) When compared with using only one alloy, using two alloys to make the ten dollar coin has certain advantages and disadvantages. Give ONE advantage and ONE disadvantage of using two alloys to make the coin. (iii)*When alloy X is heated with concentrated sulphuric acid, a bluish-green solution is formed and a colourless gas is evolved. (1) Suggest ONE metal that may be present in X. Explain your answer. (2) What is the colourless gas? Suggest a chemical test for the gas. (10 marks) 6. 97 1 For each of the tasks listed in the table below, decide which substance on the right is the best to use to accomplish the task. Explain your answer in each case.

(6 marks) 7. 98 1 Lithium is a Group I element in the Periodic Table. It occurs naturally in two isotopic forms. The relative abundance of each of these isotopes is shown in the table below: Isotope Relative abundance (%)

Li 7.4 6

Li 92.6 7

(a) What is the meaning of the term 'isotope'? (b) Calculate the relative atomic mass of lithium. (c) A piece of freshly cut lithium metal is placed in air. (i) What would be observed on the surface of the metal after some time?

Write the relevant

chemical equation. (ii) Draw the electronic diagram of the product in (i), showing electrons in the outermost shells only. (6 marks) 8. 98 8(b) The body of a can of fruit juice is made of iron coated with another metal. The top of the can and the ring-pull are made of aluminium. (i) (1) Suggest ONE reason why the iron body is coated with another metal. (2) Name ONE metal commonly used for coating the iron body. (ii) Suggest ONE reason why aluminium, rather than iron, is used for making the top of the can and the ring-pull. (iii) Explain why it is not advisable to buy cans of fruit juice (1) if the cans have scratches on the iron body. (2) if the cans are swollen. (iv) There is an increasing tendency for manufacturers to use cans made entirely of aluminium for the storage of fruit juice. Suggest ONE advantage and ONE disadvantage of using aluminium cans for the storage of fruit juice. (9 marks)

CE : Section 2 Common Metals LQ P.3

9. 99 2 For each of the following experiments, state ONE observable change and write a chemical equation for the reaction involved. (b) A small piece of calcium is placed in a Bunsen flame. (c) A mixture of copper(II) oxide and carbon powder in heated in a test tube. (4 marks) 10. 99 7(a) The table below lists the key components of three alloys. Alloy bronze steel solder

Key components copper, tin iron, carbon tin, metal X

(i) Suggest an explanation for each of the following statements: (1) Although the amount of iron in the earth crust is greater than that of copper and tin, the Iron Age occurred after the Bronze Age. (2) During the Bronze Age, people used bronze instead of copper to make tools and weapons. (3) After being exposed to air for a period of time, the surface of bronze objects turns green. (ii) Steel is an alloy of iron and carbon. Explain, in terms of structure, why the addition of carbon to iron can enhance the strength of iron. (iii) Solder is an alloy of tin and metal X. (1) What is X? (2) Explain why solder, but not tin or X, is used for joining electrical wires. (9 marks) 11. 00-3 Consider the following materials: aluminium, bronze, copper, lead, mild steel and titanium For each of the tasks below, choose the ONE material which is best to accomplish the task. Explain your choice in each case. (a) making electrical wiring (b) making overhead high voltage cables (c) making ship propellers (6 marks) 12. 00-9(a) X, Y and Z are three different metals. The table below shows the results of two experiments carried out using the metals or their oxides. Experiment Adding the metal to water Heating the metal oxide

X effervescence no observable change

Y no observable change metal produced

Z no observable change no observable change

(i) Based on the above information, arrange the three metals in order of increasing reactivity. Explain your answer. (ii) An oxide of Y has the formula YO.

When 1.08 g of this oxide is heated strongly, it decomposes

completely to give 60.0 cm of oxygen, measured at room temperature and pressure. Calculate the 3

relative atomic mass of Y. (Relative atomic mass : O = 16.0; molar volume of gas at room temperature and pressure = 24.0 dm3) (6 marks)

13. 01-5 (Essay)

CE : Section 2 Common Metals LQ P.4

Explain why anodization, sacrificial protection and tin-plating can protect metals from corrosion. (9 marks) 14. 01-7(c) The photograph below shows a diamond ring:

(i) Explain why gold and diamond each has a high melting point. (ii) 18-carat gold is an alloy of gold. Suggest ONE reason why 18-carat gold instead o pure gold is used in making the ring. (You are NOT required to consider the price of the materials.) (iii) In an experiment, a piece of 18-carat gold was heated with concentrated nitric acid. A bluish green solution was formed. (1) Suggest another metal that may be present in the 18-carat gold. Explain your answer with the help f a chemical equation. (2)State another observation in the experiment. (7 marks)