3C the Reactivity Series of Me f4

8/11/2019 3C the Reactivity Series of Me f4

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(C) The Reactivity Series

of Metal and itsApplication


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Learning Objectives:

Compare the differences in the vigour of the reaction ofsome metals with oxygen.

Deduce the reactivity series of metal. Determine the positions of carbon and hydrogen in the

reactivity series of metal.

State what the reactivity series of metals are.

Describe the various applications of the change of

oxidation number in substances. Describe the existence of various types of ores in our

country.

Describe the extraction of iron and tin from their ores.

Explain the use of carbon as the main reducing agent inmetal extraction.

Describe the contribution of metal extraction industry tothe economy of our country

Use the reactivity series of metals to predict possiblereactions involving metals.


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Reactions of Metal with Oxygen

The more rapidly the metal burns in oxygen

and the brighter the flame produced, the

more reactive the metal is with oxygen.

It is used to build up the Reactive Series of

Metals


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The Reactivity Series of Metals

The RS is a series of metals

arranged in the order of howvigorously the metals react with

oxygen


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Experiment : To deduce the reactivity series of metals

Problem Statement:

How is the reactivity series of metals deduced from the reactionsof metals with oxygen?

Hypothesis:

The more reactive a metal, the more brightly and more rapidly themetal will burn in oxygen.

Variables:

MV: Type of metalRV : The intensity of the flame

FV : The amount of metal and potassium manganate(VII) used


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Apparatus Setup:

Apparatus:

Materials:


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Procedure:

1. Two spatula of potassium manganate(VII) crystals are placed

in a boiling tube.

2. A small quantity of glass wool is then placed inside the boiling

tube to prevent potassium manganate(VII) from spilling over.

3. A spatula of zinc powder is placed on a sheet of asbestos paper

and put inside the boiling tube.

4. The boiling tube is then clamped to a retort stand.

5. The zinc powder is heated strongly.

6. When the zinc powder has become very hot, potassium

manganate(VII) is heated strongly to produce oxygen gas.

7. The intensity of the flame or glow is recorded.

8. Steps 1 to 7 are repeated by replacing zinc powder with iron

powder, lead powder, copper powder and magnesium powder.


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Results:

Metal

Observation

Intensity of flame/glowColour of

hot oxide

Colour of

cold oxide

ZnBurns rapidly

Bright glowYellow White

FeBurns less rapidlyGlow less bright than burning

of Zn

Reddish-

brown

Reddish-

brown

PbBurns slowly

Faint glowBrown Yellow

Cu Faint glow Black Black

Mg

Burns very rapidly

Very bright white flame

produced

White White


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Conclusion

The reactivity of the five metals with oxygen

is as follows:

Mg > Zn > Fe > Pb > Cu

Reactivity decreases


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The Reactivity Series of Metals


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Apparatus Setup:

Apparatus:

Materials:

Carbonpowder

+ metal oxide

Asbestos

paper


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Procedure:

1. Two spatula of carbon powder are placed on a piece of

asbestos paper.

2. One spatula of zinc oxide is added to the carbon powder. The

zinc oxide and carbon powder are mixed uniformly.

3. The asbestos paper with its contents is placed on a wire gauze

over a tripod stand.

4. The mixture of zinc oxide and carbon is heated strongly for a

few seconds.

5. After this, the Bunsen flame is removed and the mixture

examined to determine whether it will continue to glow.

6. Steps 1 to 5 are repeated by replacing zinc oxide with

copper(II) oxide and aluminium oxide


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Results:

Mixture Observation

Reactivity of

Carbon

C + ZnOThe mixture glows brightly

A grey solid is formed

C is more

reactive than

Zn

C + CuO

The mixture burns with a bright

flame

A brown solid is obtain

C is more

reactive than

Cu

C + Al2O3 No changes

C is less

reactive than

Al


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Experiment : To determine the position of hydrogen in the RS

Apparatus:

Materials:

Figure 1


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Procedure:

1. Place one spatula of copper(II) oxide, CuO into a porcelaindish.

2. Place the porcelain dish into a combustion tube and clamp thetube horizontally.

3. Set up the apparatus as shown in Figure 1

4. Pass dry hydrogen gas through the combustion tube for a fewminutes to remove the air in the combustion tube.

5. Burn the excess hydrogen gas that flows out from the smallhole of the combustion tube.

6. Heat the copper(II) oxide, CuO in the combustion tubestrongly.

7. Observe any changes that occurs. Ensure that the hydrogen gas

is contineously flowing throughout this activity.8. Repeat steps 1 to 7 using zinc oxide, ZnO, lead(II) oxide, PbO

and iron(III) oxide, Fe2O3 respectively to replace copper(II)oxide, CuO


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Results:

Mixture Observation Inference

H2+ CuO

CuO burned brightly.

The black powder turned

brown.

Copper metal formed

H > reactive than Cu

H2 + ZnO No changes H< reactive than Zn

H2 + PbO

PbO burned brightly.

The yellow powder

became shiny grey

globules.

Lead metal formed


H2+ Fe2O3

Fe2O3burned brightly.

The brown powder

became shiny grey

globules.

Iron metal formed



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Conclusion

The position of H is between Zn and Fe in the

Reactivity Series:

Zn > H > Fe > Pb > Cu

Reactivity decreases


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Position of Carbon in RS

Carbon is between Aluminium and Zinc in

RS.

Carbon will reduce the oxide of metal X if

carbon is more reactive than metal X


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Position of Hydrogen in RS

Hydrogen is between zinc and iron in RS.

The position of hydrogen can be determined

by passing the hydrogen gas over hot metal

oxide


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Uses of RS in the Extraction of Metals

K

Na

Ca

Al

C

ZnFe

Sn

Pb

Cu

Hg

Ag

Au

Very Reactive Metal

- Their ores require strong reductionthrough electrolysis

Fairly Reactive Metal

- Their ores can be reduced by heating

strongly with carbon

Less Reactive Metal

- Their ores can be reduced by heating directly in the air

Least Reactive Metals

- They exist as uncombined element


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Why carbon?

It is cheap and widely available

Carbon dioxide gas produced during the

extraction process is non-poisonous


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Common Metals and their ores

Metal Ore

Main Mineral in

ore

Calcium Limestone CaCO3

Aluminium Bauxite Al2O3

IronHematite Fe2O3

Magnetite Fe3O4

Tin Cassiterite SnO2

Lead Galena PbS

Zinc Zinc blende (sphalerite) ZnS

copper Malachite CuCO3.Cu(OH)2


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Extraction of Iron1. Production of CO2

C + O2

CO2CaCO3CaO + CO2

2. Production of CO

C + CO22CO

3. Reduction of iron ore to iron

Fe2O3+ 3CO2Fe + 3CO2

Fe3O4+ 4CO3Fe + 4CO2Fe2O3+ 3C2Fe + 3CO

Fe3O4+ 2C3Fe + 2CO24. Removal of impurities

CaO + SiO2CaSiO3

limestone sand slag


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Extraction of Tin

Two main steps involved in the

extraction of tin are:

Concentration process

Reduction process


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Concentration process

1. Tin ores is concentrated by froth floatationmethod.

2. In this process, the tin ore is crushed to a finepowder and mixed with water and special oil

in a large tank.

3. The froth contains particles of concentratedtin ore.

4. The concentrated tin ore is then dried androasted to remove impurities such as carbon,sulphur and special oils.


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Reduction Process

1. The concentrated tin ore, SnO2is mixed with

coke and heated to a hightemperature(~1360C) in a furnace.

2. During heating, SnO2is reduced by carbon to

molten tin and carbon is oxidized to CO2andCO.

SnO2 + C Sn + CO2SnO2 + 2C Sn + 2CO

3. The CO produced can also reduced SnO2to tin.

SnO2 + 2CO Sn + 2CO2


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Practice C1. The oxide of metal X can be reduced by carbon but not hydrogen.

(a) identify the metal X(b) (i) write the equation for the reaction between the oxide of

metal X and aluminium powder.

(ii) identify the oxidizing and reducing agents in this reaction

2. (a) Give two reasons why carbon is chosen as the reducing agent in

the extraction of metals

(b) Chromium is extracted from chromium(III) oxide by heating a

mixture of aluminium powder and chromium(III) oxide strongly.

(i) write the equation for the reaction that occurs in this process.

(ii) what conclusion can be made regarding the reactivity of

chromium and aluminium.

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3C the Reactivity Series of Me f4

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