Alloys & their Properties (Cambridge (CIE) O Level Chemistry): Exam Questions

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]

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]

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.

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. 

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]

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]