Properties, Uses & Alloys of Metals (Cambridge (CIE) IGCSE Chemistry)

Strontium and zinc are both metals with a valency of 2. Strontium is more reactive than zinc. Its chemistry is similar to that of calcium.

i) Complete the following table that shows the number of protons, electrons and neutrons in each particle.

[3]

ii) Explain why and  are isotopes.

[1]

Extended Only

The major ore of strontium is its carbonate, SrCO₃. Strontium is extracted by the electrolysis of its molten chloride.

i) Name the reagent that will react with the carbonate to form the chloride.

[1]

ii) The electrolysis of molten strontium chloride produces strontium metal and chlorine. Write ionic equations for the reactions at the electrodes.

negative electrode (cathode) .............. positive electrode (anode) ................

[2]

iii) One of the products of the electrolysis of concentrated aqueous strontium chloride is chlorine. Name the other two.

[2]

Both metals react with water.

i) Write a word equation for the reaction of zinc and water and state the reaction conditions.

word equation .........

[1]

conditions ............

[2]

ii) Write an equation for the reaction of strontium with water and give the reaction condition.

equation .........

[2]

condition .........

[1]

Extended Only

Gallium is a metallic element in Group III. It has similar properties to aluminium.

i) Describe the structure and bonding in a metallic element. You should include a labelled diagram in your answer.

[3]

ii) Explain why metallic elements such as gallium are good conductors of electricity.

[1]

Extended Only

Give the formula of

Gallium(III) chloride ......................................

Gallium(III) sulfate ........................................

Extended Only

Gallium(III) oxide, Ga₂O₃, is amphoteric.

i) Write the chemical equation for the reaction between gallium(III) oxide and dilute nitric acid to form a salt and water only.

[2]

ii) The reaction between gallium(III) oxide and sodium hydroxide solution forms only water and a salt containing the negative ion Ga₂O₄^2–.

Write the chemical equation for this reaction.

[2]

Alloys of gallium and other elements are often more useful than the metallic element itself.

Suggest two reasons why alloys of gallium are more useful than the metallic element.

Brass is an alloy which contains zinc.

i) Name the other metal in brass.

[1]

ii) Suggest two reasons why an alloy such as brass is preferred to either of its constituent metals.

[2]

Extended Only

In an experiment to investigate the rate of rusting of steel, three pieces of steel were used. One piece of steel was completely coated with copper, one piece was completely coated with zinc and the third piece was left uncoated. All three pieces were left exposed to the atmosphere.

i) Explain why the uncoated piece started to rust.

[1]

ii) The coating on both of the other two pieces was scratched, exposing the steel.

The piece of steel coated with zinc still did not rust but the copper-coated piece of steel rusted very rapidly.

Explain these observations in terms of the formation of ions and the transfer of electrons.

[4]

Iron from the blast furnace is impure. It contains about 4% carbon and 0.5% silicon. Most of this impure iron is used to make mild steel, an alloy of iron containing less than 0.25% carbon.

A jet of oxygen is blown through the molten iron in the presence of a base, usually calcium oxide. Explain how the percentage of carbon is reduced and how the silicon is removed. 

i) Why are steel alloys used in preference to iron?

[1]

ii) State a use of the following alloy.

Stainless steel

[1]

Extended Only

Both iron and steel have typical metallic structures - a lattice of positive ions and a sea of electrons.

i) Suggest an explanation for why they have high melting points.

[2]

ii) Explain why, when a force is applied to a piece of steel, it does not break but just changes its shape.

[2]

Vanadium is a transition element.

An atom of the most common isotope of vanadium can be represented as .

Complete the following table to show the number of protons, electrons and neutrons in each particle.

The major use of vanadium is to make vanadium steel alloys.

 i) Explain the phrase steel alloys.

[2]

ii) State the name and use of another steel alloy.

[2]

Two of the oxidation states of vanadium are +3 and +4.

 i) Write the formula of vanadium(III) oxide and of vanadium(IV) oxide.

[2]

ii) Vanadium(III) oxide is basic and vandium(IV) oxide is amphoteric. Describe how you would obtain a sample of vanadium(III) oxide from a mixture of these two oxides.

[3]

The list shows the names of some metals.

 calcium

copper

iron

magnesium

silver 

zinc

i) Identify the metal from the box that burns with a bright white flame.

[1]

ii) In the Earth, metals are found either in ores or as uncombined elements. Explain which metal from the box is most likely to be found as an uncombined element.

[2]

i) Which metal or metals from the list in part (a) will react readily in oxygen?

[2]

ii) Give an equation to show a metal reacting with oxygen. Include state symbols.

[2]

Extended Only

The diagram shows the arrangement of the particles in a pure metal.

Metals are often made into alloys to make them harder.

Explain why alloys are harder than pure metals.

Draw a diagram to support your answer.

Complete the table by naming two alloys and giving the elements used to make each alloy.

Tungsten is a useful metal. It has the chemical symbol W.

One method of extracting tungsten involves heating a tungsten compound, WO₃, with hydrogen. Water is also produced. Write the balanced symbol equation for this reaction.

Identify what has been reduced. Give a reason for your answer.

Extended Only

Tungsten alloyed with nickel and copper can be used to make protective covers for electrical sensors and missile guidance systems. Explain why this alloy is stronger than pure titanium. 

Separate: Chemistry and Extended Only

An ore of tungsten is Scheelite. The composition of this ore is 13.9% of calcium, 63.9% of tungsten and the remainder is oxygen. Calculate the empirical formula for this ore of tungsten.

Steel is formed from iron and carbon and is widely used in the construction industry.

i) Explain why steel alloys are used in preference to iron.

[1]

ii) State a use of stainless steel.

[1]

Extended Only

Both iron and steel have typical metallic structures - a lattice of positive ions and a sea of electrons.

i) Explain why iron and steel have high melting points.

[2]

ii) Explain why, when a force is applied to a piece of steel, it does not break but changes its shape.

[2]

Brass is an alloy of two metals, copper and zinc.

Which statement is correct?

Tick one box.

Separate: Chemistry and Extended Only

Acid digestion is a method used to dissolve metals into a solution which can then be analysed to determine the composition of the metal.

A 3.00 g sample of an aluminium alloy was reacted with an excess of concentrated nitric acid. The resulting mixture was made up to 250 cm³ with distilled water and analysed. The concentration of aluminium ions in the 250 cm³ solution was found to be 0.36 mol/dm³.

Calculate the percentage composition by mass of aluminum in the 3.00 g sample of aluminum alloy.

[A_r (Al) = 27]

This question is about metals and non-metals.

Compare the properties of metals and non-metals.

The Group I metals exhibit some properties that the majority of metals do not share.

Give one example of a property of Group I metals that is different from most other metals.

For each of the metals below, complete the table to identify a use of the metals and state the most important property of the metal that makes it suitable for that use.

Extended Only

An aluminium alloy containing 0.7% magnesium and 0.4% silicon by mass is used for making masts for sailing boats.

Calculate the number of moles of magnesium and silicon present in a mast with a mass of 17 kg.

[A_r (Mg) = 24;      A_r (Si) = 28]

Some metals react with cold water.

Give the balanced symbol equation for the reaction of calcium reacting with water. Include state symbols.

Separate: Chemistry and Extended Only

Using oxidation numbers, show that calcium is oxidised during the reaction with water.

A student added 20 cm³ of dilute hydrochloric acid to two boiling tubes. To one of the boiling tubes they added a small piece of calcium and to the other they added a small piece of magnesium.

State two observations that the student would make and how the observations would differ between the two boiling tubes.

The student had added the exact amount of magnesium required to react with the hydrochloric acid used. After carrying out the experiment, the student accidentally added some more magnesium. The student was surprised that the extra magnesium still reacted although the reaction was a lot slower. 

Explain these observations. Include an equation in your answer.