Occurrence of Metals

Did you know what the third most common element on our planet is?

You will most likely be surprised to know that it is Aluminium. And

while this is true, aluminium is not found on earth in its natural state,

but as various compounds. Let us learn more about the occurrence of

metals on earth.

Occurrence of Metals

So, we obtain metals from the earth’s surface, or from below earth’s

surface. However, not all metals are in their pure form. Some are

mixed with impurities and some are a mixture of various other

elements. We can actually classify the three basic ways of occurrence

of metals in our lithosphere.

Native Metals

(Source: 911 metallurgist)

A native metal is one that exists in nature (on earth’s surface) in its

actual metallic form. It can either exist in pure form or as an alloy.

Some such native metals that we can identify as such are iron, tin,

tungsten, antimony, arsenic and zinc. Native metals also include two

specific groups, namely the Gold group and the Platinum group.

● The Gold group consists of Gold, Silver. Aluminium, Mercury

and Lead

● The Platinum group consists of Platinum, Palladium, Rhodium,

Iridium, Osmium and Ruthenium

Relatively very few native metals are in existence. Only metals that

are generally less reactive can be found in their native state since they

can resist naturally occurring chemical reactions such as oxidation and

reduction. Gold, Silver and Platinum are the metals that occur in their

true native form in large quantities around the world.

Alloys

An alloy is a mixture of two metals or even one metal and another

substance, but the major component being metal. Metals usually have

some excellent properties for commercial use such as high strength

and electrical conductivity. To enhance them even further we mix

metals with another component to give them extra advantages.

Steel is an excellent example. Here Iron is mixed with a very small

amount of carbon. This gives a substance that is stronger and lighter

than just pure metal. Other such alloys are Brass ( Copper and Zinc),

Bronze (Copper and Tin), Stainless Steel ( Iron, Nickel and

Chromium) and countless more.

Ores

Now as the case may we find very few metals in our atmosphere in

their natural form. Most metals are found mixed together with other

materials and minerals. Some such materials from which we can

extract metals that we desire are known as Ores.

Hence it is important to know the most abundantly occurring ores and

the metals we extract from them. Let us take a look at some of the

most common ones found on earth and the primary metals we extract

from these ores

Aluminium

● Bauxite AlOx(OH)3-2x

● Kaolinite Al2(OH)4Si2O5

Iron

● Haematite Fe2O3

● Magnetite Fe3O4

● Iron Pyrites FeS2

Copper

● Copper Pyrite CuFeS2

● Cuprite Cu2O

● Malachite CuCO3.Cu(OH)2

Zinc

● Zinc Blende ZnS

● Zincite ZnO

● Calamine ZnCO3

Metallurgy

Now, these ores need to be processed so metals can be extracted from

them. This entire process of extracting metals from ores is metallurgy.

On a basic level, this involves three main steps, which are

● The concentration of the ore

● Isolation of the metal from the ore

● Purification process to obtain pure metal

Learn uses of important metals such as aluminum, Iron, Copper etc.

Solved Questions for You

Q: Name which one of these is a mineral of manganese?

a. Magnesite

b. Magnesium

c. Pyrolusite

d. All of the above

Ans: The correct answer is “C”. Pyrolusite is a black amorphous

mineral which consists of manganese oxide.

Concentration of Ores

So nearly all rocks on the planet have some metal or mineral content.

However, the concentration of this metal is too less for it to be

valuable. Ores usually have a very high content of the desired mineral,

but it still must be separated from other mixed impurities, this method

is known as the concentration of ores. Let us discuss this topic.

Concentration of Ores

An ore of a metal is an impure source, this means other than the metal

it consists of many other impurities such as sand, grit, clay, rocks etc.

These impurities are collectively known as gangue. Gangue is

generally commercial valueless and we must separate it from the ore.

This entire process is the concentration of ores or even dressing or

benefaction.

Now there are numerous ways to carry out the concentration of ores.

The correct method is chosen based on the physical and chemical

properties of the metal. Let us take a look at some of the most

common methods.

Learn the process of Refining the Metal.

Hydraulic Washing

This method is based on the differences in weight between the gangue

and the metal. Generally, the metal particles of the ore are heavier

than the impurities. So we use the principle of gravity separation to

separate the two.

Here crushed ore is mixed with an upward stream of running water.

The lighter particles of the gangue wash away in the running water.

The heavier metal particles settle down and can be separated easily.

We use this method for ores that contain lead and tin since these are

relatively heavier.

Browse more Topics under General Principles And Processes Of Isolation Of Elements

● Occurrence of Metals

● Thermodynamic Principles of Metallurgy

● Extractions of Crude Metal from Concentrated Ore

● Refining

● Uses of Aluminium, Copper, Zin, and Iron

Magnetic Separation

Just like we saw earlier, the physical properties of metals can allow us

to separate them from the gangue. One such physical property is

magnetic properties of metals. In this method of Magnetic Separation,

we use the magnetic properties of certain metals to divide them from

the non-magnetic gangue.

Here we place the powdered ore on a roller belt. One belt of this roller

is a magnet. So the magnetic material attracts to the metal belt and

stays on the belt. The non-magnetic gangue falls in a heap from the

belt. Also, the reverse may be the case. The gangue may be the

magnetic material in certain cases.

Iron ores and manganese ores are the main ones for which we use

magnetic separation. Magnetite and Chromitite ores (both iron ores)

use this method on a large scale to remove their impurities.

Learn the process of extracting Crude Metal from Concentrated Ore.

Froth Flotation Process

Another method of concentration of ores is the Froth Flotation

Method. This is the process for concentration of primarily sulphide

ores. It has the advantage over gravity separation because it can

collect even the extremely fine particles of minerals.

The process uses the difference in the wetting characteristics of

minerals and gangue. Minerals are generally wetted by oil and gangue

is wetted by water. So they prepare a mixture of the crushed ore with

water, oil and other substances.

And rotating paddles will then agitate such mixture and introduce air.

The air will cause bubbles to form, which attaches itself to the solid

particles of minerals. And then a froth will form and it will rise to the

top. This froth will contain the mineral particles which we can now

separate. There are three main types of additives in this process,

namely

● Collectors: These increase the non-wettability of mineral

particles. Basically, they form a film on the particles which

makes them water repellent. Some common collectors are

carboxylic acids and xanthate salts.

● Froth Stabilizers: As the name suggests, they stabilize the foam

that rises to the top, to make the separation easier. Pine oil,

soaps, cresols etc are froth stabilizers.

● Depressants: Some time two similar minerals are both found in

the ore and both react to collectors similarly. This will mean

that both will rise to the top of the foam. To separate such

similar compounds we use depressants. For example in an ore

containing both ZnS and PbS (both sulphides) we use NaCN as

a depressant. It reacts with ZnS not allowing it to froth and

only PbS comes up in the foam.

Leaching

Leaching is a chemical process of concentration of ore. Here the ore

dissolves in a chemical solution. The minerals will react and dissolve

leaving behind the impurities only which filter out. And then the

metal will be obtained from the chemical solution. Let us now take a

look at an example of how we obtain Aluminium by leaching.

Bayer Process

The leaching of aluminium from its core bauxite on an industrial scale

is known as the Bayer process. This process will give us the end

product of Alumina (aluminium oxide) from bauxite. The other

impurities of silica, titanium oxide and varies other oxides will

separate.

The first step is to heat the bauxite ore to temperatures of 200°c along

with a sodium hydroxide solution. This will convert the aluminium

oxide to a solution of sodium aluminate. The silica will dissolve itself

in the process. The chemical equation is

Al2O3 + 2 NaOH → 2 NaAlO2 + H2O

From the above solution, we remove solid impurities by filtration.

Then we bubble carbon dioxide through the aqueous solution of

sodium aluminate to neutralize it. And aluminium hydroxide

precipitates as a result.

2 NaAlO2 + CO2 → 2 Al(OH)3 + Na2CO3 + H2O

This hydrated alumina is then heated to 1470 K. This gives us a pure

form of aluminium hydroxide without the impurities.

2 Al(OH)3 → Al2O3 + 3 H2O

Read Uses of Aluminium, Copper, Zinc and Iron here.

Solved Question for You

Q: Which one of the following ores do we concentrate by chemical

leaching method?

a. Galena

b. Copper Pyrite

c. Cinnabar

d. Argentine

Sol: Gold and silver ores are concentrated by leaching. In this method,

we treat the ore with a suitable reagent in which ore is soluble but

impurities do not. Thus, impurities are removed by filtration.

Among galena, copper pyrites, cinnabar and Argentine, Argentite

being silver ore is concentrated by chemical leaching method.

Thermodynamic Principles of Metallurgy

So as you know metals are the basis of our modern life.

Advancements made by man even in the pre-historic age was down to

the discovery of metals. The extraction of metals from the lithosphere

is what we call metallurgy. And chemists take help of thermodynamic

principles to help with this process. Let us take a look at the

thermodynamic principles of metallurgy.

Thermodynamics

There is an overlap between the study of physics and chemistry,

known as Physical Chemistry. And here is where the concept of

thermodynamics exits. Thermodynamics is the branch of science that

deals with a relationship between thermal energy i.e. heat and other

forms of energy.

Thermodynamics is the study of the energy transfer that occurs during

chemical as well as physical changes. It also allows us to predict and

measure these changes.

Browse more Topics under General Principles And Processes Of Isolation Of Elements

● Occurrence of Metals

● Concentration of Ores

● Extractions of Crude Metal from Concentrated Ore

● Refining

● Uses of Aluminium, Copper, Zin, and Iron

Thermodynamics in Metallurgy

The main thermodynamic concept we must concern ourselves with

when it comes to metallurgy is Gibbs Free Energy. In

thermodynamics, whether a process will happen spontaneously or not

will be determined by Gibbs Free Energy. The symbol ΔG. If this

value of ΔG is negative then the reaction will occur spontaneously.

We will now look at two equations to arrive at ΔG

ΔG = ΔH – TΔS

ΔH is the change in enthalpy. Here a positive value will depict an

endothermic reaction, while a negative value will be an exothermic

reaction. So when the reaction is exothermic, it makes ΔG negative.

ΔS is the Entropy or the randomness of molecules. This changes very

sharply when the state of the matter changes. Another equation which

relates the Gibbs Free Energy to the equilibrium constant is

ΔG° = RTlnKeq

Keq is the equilibrium constant. It is calculated by dividing the active

mass of products by the active mass of reactants. R is the universal gas

component. Now to attain a negative value of ΔG (which is desirable)

the value of the equilibrium must be kept positive.

Ellingham Diagram

An Ellingham diagram shows the relation between temperature and

the stability of a compound. It is basically a graphical representation

of Gibbs Energy Flow.

In metallurgy, we make use of the Ellingham diagram to plot the

reduction process equations. This helps us to find the most suitable

reducing agent when we reduce oxides to give us pure metals. Let us

take a look at some important properties of the Ellingham Diagram

● Here ΔG is plotted in relation to the temperature. The slope of

the curve is the entropy and the intercept represents the

enthalpy.

● As you know the ΔH (enthalpy) is not affected by the

temperature

● Even ΔS that is the entropy is unaffected by the temperature.

However, there is a condition here, that a phase change should

not occur.

● We will plot the temperature on the Y-axis and the ΔG on the

X axis

● Metals that have curves at the bottom of the diagram reduce the

metals found more towards the top

The reaction of metal with air can be generally represented as

M (s) + O2 (g) → MO (s)

Now when reducing metal oxides the ΔH is almost always negative

(exothermic) reaction. Also since in the reaction (as seen above), we

are going from the gaseous state to the solid state ΔS is also negative.

Hence as the temperature increases, the value of TΔS will also

increase, and the slope of the reaction goes upwards

Exceptions to Ellingham Diagram

There are cases when the entropy is not negative, and the slope will

not be upwards. Let us take a look at few such examples

● C(s) + O2 (g) → CO2 (g): Entropy of solids is negligible. So

here one molecule of gas is resulting in one molecule of gas.

Hence there is almost no net entropy. So there will be no slope,

it is completely horizontal.

● 2C (s)+ O2 (g) → 2CO (g): Here one mole of gas is giving you

two moles of gas as products. So here the entropy will be

positive. And as a result, this curve will go downwards.

Limitations of Ellingham Diagram

● It does not consider the kinetics of the reactions.

● Also, it does not provide complete information about the oxides

and their formations. Say for example more than one oxide is

possible. The diagram gives us no representation of this

scenario

Uses of Ellingham Diagram

1) Alumino Thermic Process

The Ellingham curve on the graph actually lies lower than most of the

other metals such as iron. This essentially means Aluminium can be

used as a reducing agent for oxides of all the metals that lie above it in

the graph. Since aluminium oxide is more stable it is used in the

extraction of chromium by a thermite process.

2) Extraction of Iron

Extraction of iron from its oxide is done in a blast furnace. Here the

ore mixes with coke and limestone in the furnace. Actually, the

reduction of the iron oxides happens at different temperatures. The

lower part of the furnace is kept at a much higher temperature than the

top. This process was developed after understanding the reactions with

the help of thermodynamics. These reactions are as follows

At temperatures of 500-800 K

3Fe2O3 + CO → 2 Fe3O4 + CO2

Fe3O4 + 4CO → 3Fe + 4 CO2

Fe2O3 + CO → 2FeO + CO2

At temperatures of 900-1500 K

C + CO2 → 2CO

FeO + CO → Fe + CO2

Solved Question for You

Question: In which of the following pair of metals, both are

commercially extracted from their respective ores by carbon reduction

method?

a. Zn, Cu

b. Fe, Cu

c. Sn, Zn

d. Fe, Zn

Answer: The correct option is “C”. The oxide ores of Tin and Zinc are

reduced with carbon to form metals. And so Tin and Zinc are

commercially extracted from their respective ores by carbon

reduction.

Extraction of Crude Metal from Concentrated Ore

Metals are incredibly useful substances. It is well accepted that our

technologically advance lives would not be possible without metals.

Their physical properties such as electric conductivity, density,

malleability etc make them perfect for industrial use. Now let us take a

look at extraction of metals from their ores.

Extraction of Metals

Now we already saw how the ore of a metal is concentrated to remove

impurities known as gangue. After concentration of ores, we must

now extract metal from in it. This step will give us metal in its pure

form i.e. the native form of metal.

First, we must convert the ore to a suitable form. The metals need to

be in an oxide form for the reduction process to be easier. Hence the

ores are converted to oxides, so it is ideal for reduction. After doing so

the ores will undergo reduction, to give us metal. Therefore the two

main steps of extraction of metals are,

● Convert Ores to form oxides

● Reduction of Metal Oxides

Browse more Topics under General Principles And Processes Of Isolation Of Elements

● Occurrence of Metals

● Concentration of Ores

● Thermodynamic Principles of Metallurgy

● Refining

● Uses of Aluminium, Copper, Zin, and Iron

Convert Ores to Oxides

It is easier to reduce oxides than say sulphides. Oxygen is more

electronegative than other elements. So it is easier for oxides to accept

an electron pair and get reduced. There are various ways to carry out

this step. Let us take a look at them

1] Calcination

This is the process of heating a substance in a limited supply of air or

oxygen. We subject the ore to thermal energy (heat) so we can change

their chemical state and turn them into oxides. Although we must

ensure that we keep the temperatures below the melting point of the

metal. Hydroxides and carbonates are usually converted to oxides via

this process. Here is how an iron ore is converted to iron oxide, to then

later enable reduction

Fe2O3.xH2O → Fe2O3 (solid) + H2O (gas)

2] Roasting

Roasting is another way to convert compounds to oxides. It is a

metallurgical process involving gas-solid reactions at elevated

temperatures with the goal of purifying the metal component. In

roasting the ore is heated up in the furnace in a regular supply of air.

Again we ensure that the temperatures are within the melting point of

the metal.

Here the oxygen in the air reacts with the sulphide ores to give us

oxides. The sulphur in the ore forms sulphur dioxide and separates

out. Here is a Zinc Sulphide chemical reaction

2ZnS + 3O2 → 2ZnO + 2SO2

Reduction of Metal Oxides

This is the second step in the extraction of metals from their respective

ores. Now once we obtain metal oxides from the ores, they must now

reduce them. Again in this reduction process, we heat the metal oxide.

But this time we add a reducing agent. This reducing ageing is usually

Carbon or a carbon compound. This is because they react best with

oxygen and are readily and cheaply available.

Now when the carbon reacts with the metal oxide reduction takes

place, This is when electron gain or electronation occurs. This means

the carbon combines with the oxygen, leaving us with a pure metal.

The general reaction for reduction is as follow

MxOy + yC → xM + CO

To chose the ideal reducing agent for a certain ore, and to also find out

the correct amount of thermal energy requirement we must depend on

Giggs Energy interpretations. We represent these graphically using an

Ellingham Diagram.

Solved Question for You

Q: In the extraction of copper from its sulphide ore, the metal forms

by reduction of Cu2O with which of the following?

a. ZnS

b. CO

c. Cu2S

d. None of the above

Ans: The correct option is “C”. Compounds of certain metals reduce

to metals without using any additional reducing agent ores of Cu, Pb,

Hg etc. Their sulphide ores are partially roasted to give some oxide.

This oxide is now reduced to the metal by the remaining sulphide ore

at elevated temperatures in the absence of air. This process is what we

call self-reduction.

Cu2S + 2Cu2O →6Cu + SO2

Refining

When we say that gold is 24 carats, what does it mean? It means that

the gold is completely absent from impurities, it is entirely pure. Now,

this does not happen naturally. Metals extracted or mined always have

some impurities in them. The process of removing such impurities is

known as refining. Let us learn more about it.

Refining of Metals

In metallurgy refining of metals is the final process. Once the

extraction process is complete we must ensure that the metal is free of

any impurities. If you remember we have done a similar process

before of removing impurities during concentration of ores. However,

in the refining process, the chemical composition of the metal will

remain unchanged.

There are various ways to make a metal pure. Which refining method

is to be chosen will depend on the physical and chemical properties of

a particular metal. Let us explore a few common methods of refining

of metals.

Browse more Topics under General Principles And Processes Of Isolation Of Elements

● Occurrence of Metals

● Concentration of Ores

● Thermodynamic Principles of Metallurgy

● Extractions of Crude Metal from Concentrated Ore

● Uses of Aluminium, Copper, Zin, and Iron

Distillation

Certain metals such as Zinc and Mercury have a very low boiling

point. So on heating them they very readily vaporize. And of course,

they leave behind their impurities. The impure metal is heated beyond

its melting point in a furnace and the vapors are reconverted to metals

once the impurities are separated.

Learn more about the Uses of Zinc, Aluminium, and Copper here.

Liquidation

Again suitable for metals with low melting points for example tin. In

this process, we heat the impure metal and then we let it flow on a

sloped surface. The impurities will remain behind and the pure metal

will collect at the bottom of the slope.

Electrolytic Refining

This is one of the most common and widely used methods because it

is applicable to most metals. In this method, we use the different

electrochemical properties of the metals and the impurities to our

advantage.

In this process, the impure metal is the anode. The cathode is a sheet

of the pure metal. The electrolyte is the solution of the salt of the same

metal. Then we pass an electric current through the solution. The pure

metal from the anode will dissolve in the electrolyte bath and then

collect at the anode. The impurities will either dissolve or be found in

a heap at the base of the anode.

Copper refining is done by the electrolytic process. Its impurities of

iron and zinc will dissolve in the copper sulphate solution. And its

other impurities of gold or silver or platinum will remain behind.

Zone Refining

Zone refining is a special method we use to purify metals. It was the

invention of William Pfann. It purifies metals to a very high degree. A

rod of impure metal is placed in a container which we fill with inert

gas. Then we place a circular heater around the rod at the top.

The impure metal heats up due to the circular heater. Then when the

heater shifts to the next zone, the pure metal cools and crystallizes.

The molten impurities move along with the movement of the heater

and shift to the next zone. These impurities collect in the last zone and

then we can separate them.

Chromatographic Method

This follows the principles of chromatography. Chromatography deals

with the movements of components at different rates in a mixture

and/or differential absorption of an absorbent.

In this process, impure metal is put in a medium (liquid or a gas).

Then we move the medium through an absorbent. Different

components of the impure metal are will absorb at different levels.

And then the components that were absorbed are removed by using a

suitable solvent.

There are various forms of this method, like Column Chromatography

(where we use Al2O3), Thin Layer Chromatography, Gas-liquid

chromatography etc.

Learn more about Extraction of Metal from Concentrated Ore here.

Solved Example for You

Q: We can obtain highly pure metal by zone. True or False?

Ans: Zone refining or Fractional Crystallization is the method

employed to get metal of very high purity i.e ultrapure samples of Ge,

Si, B, Ga etc. This method is based on the fact that impurities are more

soluble than the pure metal in the melt. So the above statement is

True.

Uses of Aluminium, Copper, Zinc and Iron

Did you know that we describe periods of history according to the

metal that was in use during the said period? The Stone age was

followed by the Bronze Age and the Iron Age. All modern

developments can be traced back to our discovery and effective use of

metals. Let us learn about the uses of very important metals such as

aluminium, Iron, Copper etc.

Uses of Aluminium

Aluminium has some distinct physical properties. It is a soft metal and

is very malleable. In fact, it is the second most malleable metal. It is

also a non-toxic metal. This results in a large variety of household

uses of aluminium. In our everyday use, we will see aluminium use in

cans, foils and kitchen utensils.

Aluminium is also non-corrosive and non-magnetic. And although by

itself it isn’t very strong, it makes very strong alloys with copper and

magnesium. These are lightweight alloys and yet have great strength.

And so they are an important part in the building of aeroplanes and

aircraft. In it also used in satellite dishes!

Aluminium is also a great conductor of electricity. And it is much

cheaper than its counterpart Copper. So we often use aluminium in

electric wires and other such power transmission lines.

At certain times we make use of Aluminium in construction as well. It

requires less maintenance as it is corrosion resistant. The first building

whose aluminium use was recorded was indeed the Empire State

Building in New York.

Browse more Topics under General Principles And Processes Of Isolation Of Elements

● Occurrence of Metals

● Concentration of Ores

● Thermodynamic Principles of Metallurgy

● Extractions of Crude Metal from Concentrated Ore

● Refining

Uses of Copper

Copper is the red-hued metal with atomic number 29. Like most

metals copper is a very good conductor of heat and electricity. It is

also malleable and ductile. Its most distinct feature is its excellent

ability to make alloys with other metals.

These above characteristics make copper a very useful metal to

humankind. Actually copper has been in regular use since almost 8000

BC, where coins and ornaments were made from copper. In the

modern day, the most important use of copper is in wiring for

electronic devices such as computers and mobile phones. Also,

conductors, transformers and other systems of distribution of power

depend on copper due to its excellent conductivity.

It is also an essential metal in plumbing systems. Copper is also a

major component in the manufacturing of cars. They are found in the

radiators, oil coolers and even in the braking systems. And in the

newer cars, it is also an important element of the navigation systems.

However, copper is invaluable when we combine it with other metals

to make excellent alloys. Bronze is one such alloy we get when we

mix copper with tin. The uses of bronze are limitless. Another alloy of

great importance is Brass made by combing copper and zinc.

Uses of Zinc

Zinc is a bluish metal. It is actually a hard and brittle metal. It can be

malleable between 100° to 150° C but is hard at other temperatures. In

comparison to other metals, it has a relatively low melting as well as

the boiling point. Zinc is also fairly non-corrosive

One of the most important uses of zinc is its suitability to be used in

Galvanization. A thin layer of zinc coats other metals such as iron. It

protects the iron from corrosion. Also since Zinc is a more reactive

metal it acts as a sacrificial metal. The oxygen in the air reacts with

Zinc to form Zinc Oxide, thereby protecting the iron.

Zinc also makes alloys with vast uses such as Brass and nickel silver.

It also is used in the manufacturing of die-casting. An important

compound of zinc, Zinc Sulphide (ZnS) is the main element in the

production of luminous paints. Its applications are in X-ray machines

and television screens.

Uses of Iron

Iron is the single most important metal on this planet. It is a fact that

nearly 90% of the total metal refined by us is Iron. An actually it is a

great contradiction that the metal most widely used is also highly

corrosive. But its importance arises from the fact that it makes the

most important alloy which is Steel.

Iron like all metals is a great conductor of thermal and electric energy.

It is also malleable and ductile both. In its pure form iron is actually a

soft material, which means it can be shaped easily. Pure iron is also

highly reactive to be of much use.

Steel

Manufacturing of steel requires iron. Steel is an alloy of iron and

carbon. The composition of the various elements differs according to

the various types of steel. Every type has its own unique uses.

Carbon Steel: The composition of carbon is between 0.1% to 2.1%. It

has a vast array of uses. Mild carbon steel is used in making fences

and barbed wires. And medium carbon steel is suitable for

construction purposes. The steel we use in bridges and buildings is

medium carbon steel. High carbon steel is quite brittle but can be used

to make wires.

Stainless Steel: The main component of stainless steel along with iron

is at least 10.5% of chromium. This chromium makes a thin layer on

the steel, to prevent rusting. It also consists of small amounts of

carbon, silicon, and manganese. Stainless Steel is used for everything

from power generation to making utensils. It is an important part of

the food storage industry. And lastly, it is even used in construction as

a part of roofing, windows, and facades.

Learn more about Extraction of Metal from Concentrated Ore here.

Solved Question for You

Q: Zinc is used in galvanizing since iron forms ions ______ readily

than zinc.

a. less

b. high

c. equal

d. none of the above

Ans: The correct answer is option “A”. As the oxidizing potential of

Iron is less than Zinc, it has a low tendency to oxidize than zinc.