ਹੁਕਮਨਾਮਾ ਸ਼੍ਰੀ ਦਰਬਾਰ ਸਹਿਬ ਸ਼੍ਰੀ ਅੰਮ੍ਰਿਤਸਰ ਸਹਿਬ ਤੋਂ ਜੀ ਅੱਜ ਦਾ ਮੁੱਖਵਾਕ : Hukamnama Sri Darbar Sahib Sri Amritsir Sahib Ji Ton Aj Da Mukhwak: 05,04,2015

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ANG=>676

ਧਨਾਸਰੀ ਮਹਲਾ ੫ ॥
धनासरी महला ५ ॥
Dhanaasaree, Fifth Mehl:

ਮੋਹਿ ਮਸਕੀਨ ਪ੍ਰਭੁ ਨਾਮੁ ਅਧਾਰੁ ॥
मोहि मसकीन प्रभु नामु अधारु ॥
I am meek and poor; the Name of God is my only Support.

ਖਾਟਣ ਕਉ ਹਰਿ ਹਰਿ ਰੋਜਗਾਰੁ ॥
खाटण कउ हरि हरि रोजगारु ॥
The Name of the Lord, Har, Har, is my occupation and earnings.

ਸੰਚਣ ਕਉ ਹਰਿ ਏਕੋ ਨਾਮੁ ॥
संचण कउ हरि एको नामु ॥
I gather only the Lord's Name.

ਹਲਤਿ ਪਲਤਿ ਤਾ ਕੈ ਆਵੈ ਕਾਮ ॥੧॥
हलति पलति ता कै आवै काम ॥१॥
It is useful in both this world and the next. ||1||

ਨਾਮਿ ਰਤੇ ਪ੍ਰਭ ਰੰਗਿ ਅਪਾਰ ॥
नामि रते प्रभ रंगि अपार ॥
Imbued with the Love of the Lord God's Infinite Name,

ਸਾਧ ਗਾਵਹਿ ਗੁਣ ਏਕ ਨਿਰੰਕਾਰ ॥ ਰਹਾਉ ॥
साध गावहि गुण एक निरंकार ॥ रहाउ ॥
The Holy Saints sing the Glorious Praises of the One Lord, the Formless Lord. ||Pause||

ਸਾਧ ਕੀ ਸੋਭਾ ਅਤਿ ਮਸਕੀਨੀ ॥
साध की सोभा अति मसकीनी ॥
The Glory of the Holy Saints comes from their total humility.

ਸੰਤ ਵਡਾਈ ਹਰਿ ਜਸੁ ਚੀਨੀ ॥
संत वडाई हरि जसु चीनी ॥
The Saints realize that their greatness rests in the Praises of the Lord.

ਅਨਦੁ ਸੰਤਨ ਕੈ ਭਗਤਿ ਗੋਵਿੰਦ ॥
अनदु संतन कै भगति गोविंद ॥
Meditating on the Lord of the Universe, the Saints are in bliss.

ਸੂਖੁ ਸੰਤਨ ਕੈ ਬਿਨਸੀ ਚਿੰਦ ॥੨॥
सूखु संतन कै बिनसी चिंद ॥२॥
The Saints find peace, and their anxieties are dispelled. ||2||

ਜਹ ਸਾਧ ਸੰਤਨ ਹੋਵਹਿ ਇਕਤ੍ਰ ॥
जह साध संतन होवहि इकत्र ॥
Wherever the Holy Saints gather,

ਤਹ ਹਰਿ ਜਸੁ ਗਾਵਹਿ ਨਾਦ ਕਵਿਤ ॥
तह हरि जसु गावहि नाद कवित ॥
There they sing the Praises of the Lord, in music and poetry.

ਸਾਧ ਸਭਾ ਮਹਿ ਅਨਦ ਬਿਸ੍ਰਾਮ ॥
साध सभा महि अनद बिस्राम ॥
In the Society of the Saints, there is bliss and peace.

ਉਨ ਸੰਗੁ ਸੋ ਪਾਏ ਜਿਸੁ ਮਸਤਕਿ ਕਰਾਮ ॥੩॥
उन संगु सो पाए जिसु मसतकि कराम ॥३॥
They alone obtain this Society, upon whose foreheads such destiny is written. ||3||

ਦੁਇ ਕਰ ਜੋੜਿ ਕਰੀ ਅਰਦਾਸਿ ॥
दुइ कर जोड़ि करी अरदासि ॥
With my palms pressed together, I offer my prayer.

ਚਰਨ ਪਖਾਰਿ ਕਹਾਂ ਗੁਣਤਾਸ ॥
चरन पखारि कहां गुणतास ॥
I wash their feet, and chant the Praises of the Lord, the treasure of virtue.

ਪ੍ਰਭ ਦਇਆਲ ਕਿਰਪਾਲ ਹਜੂਰਿ ॥
प्रभ दइआल किरपाल हजूरि ॥
O God, merciful and compassionate, let me remain in Your Presence.

ਨਾਨਕੁ ਜੀਵੈ ਸੰਤਾ ਧੂਰਿ ॥੪॥੨॥੨੩॥
नानकु जीवै संता धूरि ॥४॥२॥२३॥
Nanak lives, in the dust of the Saints. ||4||2||23||

ੴ -=ਵਾਹਿਗੁਰੂ ਜੀ ਕਾ ਖਾਲਸਾ-ਵਾਹਿਗੁਰੂ ਜੀ ਕੀ ਫਤਹਿ ਜੀ=-ੴ :
ੴ -=waheguru ji ka khalsa waheguru ji ki fateh jio=-ੴ

General Principles and Processes of Isolation of Elements (Metallurgy and its Principles)

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Electrochemical Principles of Metallurgy:

1.     For simple electrolysis when a salt in molten form is electrolysed using suitable electrodes, metal ion Mⁿ⁺ is deposited at cathode. Sometimes a suitable electrolyte is also used to decrease the melting point and to increase the conductivity of the melt.

2.     Electrolysis of molten NaCl gives Na metal and Cl₂ gas. Electrolysis of aqueous NaCl using Hg cathode and graphite anode gives Na at cathode and Cl₂ at anode.

Extraction of Aluminium (Electrometallurgy): Extraction of highly reactive metals such as Na, K, Ca, Mg, Al, etc, by carrying electrolysis of one of the suitable compound in fused or molten state.

Bauxite Al₂O₃.2H₂O is converted to alumina (purified Al₂O₃) by leaching. A mixture of 3-5% Al₂O₃, 3-8% CaF₂ (Flux), 80-85% cryolite, Na₃AlF₆ (main electrolyte) and 3-8% AlF₃ is electrolysed using steel cathode lined with carbon and graphite anode. Molten Al (99.5%pure) is tapped from the bottom. The method is commonly known as Hall method. The reaction can be written as

Cathode: Al³⁺ (melt) + 3e^- ------> Al (l)

Anode: C (s) + O^2- (melt) -----> CO (g) + 2e^-

              C (s) + 2O^2- (melt) ------> CO₂ (g) + 4e^-

The overall reaction is

2Al₂O₃ + 3C ------> 4Al + 3CO₂

For the production of about 1 kg of Al, 0.5 kg of carbon of anode is used up.

Hydrometallurgy: When metal is collected from the material obtained by the application of leaching by using some reducing agent through displacement reaction, the process is called hydrometallurgy.

1.     Extraction of Au or Ag from native ore: Leaching is carried out with 0.2 to 0.5% NaCN and zinc dust is used as reducing agent.

4Au(s) + 8CN^-(aq) + 2H₂O (ag) + O₂ (g) -----> 4[Au(CN)₂]^-(ag) + 4OH^-(ag)

Zn(s) + 2[Au(CN)₂]^-(ag) -----> 2Au(s) + [Zn(CN)₄]^2-(ag)

2.     Extraction of Ag from argentite or silver glance (Ag₂S): The same method as mentioned above is used. In the absence of O₂, the reaction is reversible.

Ag₂S + 4NaCN + 2O₂ -----> Na₂SO₄ + 2Na[Ag(CN)₂]

2Na[Ag(CN)₂] + Zn -----> Na₂[Zn(CN)₄] + 2Ag

The process is commonly known as Mac Arthur Forrest cyanide method.

Thermodynamical Principle of Metallurgy:

Gibbs free energy for a reaction is given by the equation ΔG = ΔH – TΔS and

ΔG° = -RT lnK. Negative value of ΔG and positive value of K favour the formation of products.

The reaction Cr₂O₃(s) + 2Al(s) ----->  Al₂O₃ + 2Cr(s); ΔG = -421 KJ is the thermodynamically feasible but does not take place at room temperature, because unless the temperature is so high to melt Cr(s) to liquid form, TΔS will not overcome ΔH.

If any product of a reaction having positive value of ΔG₁ can be used up by another reactant to carry out a reaction having negative value of ΔG₂, the two reactions can occur together (coupling of reactions) only if the numerical value of ΔG₂ is greater than ΔG₁.

                              2FeO ------> 2Fe + O₂ ;          ΔG_{1250 k} = 320 KJ mole^-1

                               2C(coke) + O₂ -----> 2CO ;   ΔG_{1250 k} = -430 KJ mole^-1

Net reaction, 2FeO + 2C -----> 2Fe + CO₂ ;     ΔG_Net = -110 KJ

General Principles and Processes of Isolation of Elements (Refining of metals)

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Refining: Refining of metal depends upon the nature of the metal and nature of impurities. Commonly used methods are given below.

1.     Liquation: Impure metal that has low melting point e.g., Pb, Sn etc., are heated in a furnace having sloping base. The low melting metal flows down leaving high melting impurities in the furnace.

2.     Distillation: Impure metal that has low boiling point e.g., Zn, Cd, Hg etc., are purified by distillation.

3.     Oxidative refining: If the impurities can be easily oxidised, oxidative refining is used for the purification of metal. For example, pig iron and cast are converted to wrought iron by oxidative refining using Bessemer converter.

4.     Poling: This method is used to purify a metal that has its oxide as impurity, e.g., Cu and Sn. The molten metal is stirred with green logs of wood (best is bamboo) the hydrocarbon (mainly CH₄) produced by logs of wood reduce the metal oxide to metal.

3Cu₂O + CH₄ -----> CO + 2H₂O +6Cu

5.     Electro refining: In this method, blocks of impure metal are taken as anode and strips of pure metal at cathode. Electrolyte is aqueous solution of some suitable salt of the same metal. On passing current, impure metal from anode gives metal ions into the solution and from the solution the metal ions produce metal at cathode. Sometimes the waste under the anode (anode mud) may contain precious metals, as in case of copper, the anode mud may contain gold and silver.

At anode     Cu --------> Cu⁺⁺ + 2e^-

                     (Impure)

At cathode Cu⁺⁺ + 2e^- -------> Cu

                                                 (Pure)

6.     Vapour phase refining: In this process, metal is converted to a stable volatile compound to a stable volatile compound which on strong heating produces pure metal.

 Van Arkel method: This method is used to collect ultra pure titanium and zirconium by using I₂ as specific reagent.

              

Ti   +   2I₂    --------->    TiI₄

^{(Impure)                   523K              (Volatile)}

TiI₄    ------->    Ti   + 2I₂

                         ^(Pure)

Zr(s)   + 2I₂ (g)    -------->   ZrI4 (g)

                               ^{870K             (Volatile)}

ZrI4 (g)   --------->   Zr(s)   + 2I2 (g)

                   ^2070K

 Mond’s process: This method is used to purify nickel. The reagent used is carbon monoxide.

  Ni + 4CO -----------> Ni(CO)₄

^{(Impure)              330-350K            (Volatile)}

Ni(CO)₄ --------> Ni + 4CO

                              ^(Pure)

7.     Zone refining: Semiconductors, like Si, Ge, Ga etc., are purified by this method.

The underlying principle is that, impurities are highly soluble in molten metal and pure metal solidifies easily. The method is basically fractional crystallization.

A circular heater surrounds a rod of impure metal. The heater is moved forward. The pure metal crystallises out and impurities pass into the adjacent molten metal. The method is repeated to shift the impurities to one end which is cut off.

8.     Chromatographic method: The underlying principle is the differential adsorption of different components on an adsorbent. Different types are column chromatography, paper chromatography, thin layer chromatography, etc.

In column chromatography a glass tube is packed with a suitable adsorbent such as Al₂O₃, silica, etc. The mixture to be separated is either liquid or is taken as solution in suitable solvent.

It is put at the top of the column. More adsorb able component moves down slowly. After some time, when the separation of components is visible in the column, the eluent (solvent) is poured from the top. The component which is least adsorbed is collected at the bottom, the first, followed by the other components.

General Principles and Processes of Isolation of Elements (ELLINGHAM DIAGRAMS & ITS APPLICATIONS)

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ELLINGHAM DIAGRAM

Ellingham plotted graphs of formation of oxides, sulphides and halides versus temperature. The plots of ΔfG(metal oxide)  per mole of oxygen versus temperature are useful in deciding the reducing agent and temperature for reducing a specific metal oxide. All these graphs have positive slopes showing decrease of entropy except for the formation of CO(g) from coke that shows increase in entropy with increase in temperature.

A sudden increase in slope, as in case of Zn or Mg, indicates melting. The temperature at which two graphs intersect give ΔG=0 for the reaction of one oxide with other element. The element of the lower graph works as reducing agent for the oxide of the other, e.g., Below temperature 1623K (approx) Mg metal will reduce Al2O3 (but not economical) and above this temperature it is Al that reduces MgO (but not economical).

The limitations of this method are that it does not discuss the rate of reaction and takes every reaction as an equilibrium process.                                                                                                                                 

APPLICATION OF THE ELLINGHAM DIAGRAMS

Extraction of Iron:-

                                            In Ellingham diagram, the graph of CO à CO2 conversion remains below Fe à Fe2O3 upto 1123K (for Fe à FeO). It is 1073K approximately. So, CO(g) acts as reducing agent upto this temperature.

3Fe2O3 + CO ----> Fe3O4

Fe3O4 + CO ----> 3FeO + CO2

FeO + CO ----> Fe + CO2

Also, graph of C à CO is below the graph of Fe à Fe2O3 after 1123K. So, carbon acts as reducing agent above this temperature.

Fe2O3 + C ----> 3CO + 2Fe

Zones in Blast furnace: Near the bottom coke id filled and in the upper part 8:4:1 proportion of Fe2O3, coke and lime stone. Height of blast furnace is about 150 feet.

(a)      Zone of combustion: Near the bottom, hot air is blown that burns coke to produce a temperature of 2100-2200K.

C + O2 ----> CO2 + 393.5KJ

(b)       Zone of heat absorbtion: Upgoing CO2 reacts with coke to reduce to temperature to about 1500-1600K.

C + CO2 ----> 2CO – 163KJ

(c)       Zone of reduction:  Upto 1123K, reduction of Fe2O3 by CO gas gives Fe (in the upper part). Left of Fe2O3 is reduced by coke above 1123K.

(d)      Zone of slag formation: Slagging operation takes place at about 1273K.

CaCO3   ---->   CaO + CO2

CaO   +   SiO2    ---->    CaSiO3

                Impurity

At the base molten iron is collected under the slag. This iron is called pig iron and contains about 4% carbon with many other impurities like, S, P, Si, Mn, etc.

The metal iron is collected from slag by pressing under rollers. The height of the furnace used for the extraction of Fe from Fe2O3 or Fe3O4, is about 150 feet to 200 feet.

Other Forms of Iron

• Cast Iron: It is hard but brittle form of raw iron produced by melting and cooling of pig iron, its colour is gray. Fast cooling keeps the impurity of carbon as graphite. Slow cooling converts most of the carbon into cementite Fe3C and the colour becomes white. The carbon content in cast iron comes down to about 3%. It is of two types:

1. White Cast Iron: Carbon is present in the form of cementite (Fe3C). Slow cooling of molten pig iron.
2. Grey Cast Iron: Carbon is present in the form of Graphite (Sudden cooling of molten pig iron).

• Wrought iron or malleable iron: It is prepared by heating cast iron in reverberatory furnace lined with haematite which oxides carbon to CO. Lime stone is added to remove Si, S and P as slag. The wrought iron is separated from slag by passing through rollers. It is the purest form of iron and contains carbon only upto 0.5%.

• Steel: It contains 0.1 to 1.7% carbon and remaining iron only. It is commonly prepared in Bessemer converter or open hearth furnace or electric furnace and also by Semen Martin process.

                                                            In this process calcium phosphate Ca3(PO4)2 forms as slag which is also known as Thomous slag and is used as fertilizers. Steel

is of three types:

1. Mild Steel: Also known as soft steel contains lower percentage of
   carbon which is about 0.025 to 0.25% .
2. Hard Steel: Contains maximum percentage of carbon which is about 2.5 to 5% .
3. Alloy Steel: Composition of steel which contain 0.25 to 2.5% of carbon.

General Principles and Processes of Isolation of Elements (Extraction of metals and non-metals)

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Concentration of ore:

                                        Removal of the unwanted materials (for example, sand, clays, and so on.) from the ore is known as concentration, dressing or benefaction. It involves several steps and selection of these steps depends upon the differences in physical properties of the compound of the metal present and that of the impurity. Different non-metals are extracted by de-electronation using different processes. Metals are extracted by electronation using definite methods as mentioned below.

1. Pulverisation:- The lumps of the ore are converted to small pieces by using jaw crushers and to powder by employing stamp mill or ball mill.                                                                                                                                                                                                                                     
2.  Magnetic Separation:- This method id employed to separate the magnetic and non-magnetic components present in the ore by carrying the powdered ore on a conveyer belt passing over an electromagnetic roller. This is based on differences in magnetic properties of the ore components. The non-magnetic part is thrown away while the magnetic part makes a heap below the magnet. For example, magnetic impurity of wolframite (FeWO4) is separated from tin stone ( the ore of tin). Other cases are chromite ore (FeO.Cr2O3) , magnetite (Fe3O4), pyrolusite(MnO2), etc are magnetic.                                                                
   
                                                                                                                          
3. Hydraulic Washing ( gravity separation method):- This is based on the differences in gravities of the ore and the gangue particles. This method is employed to purify heavier ore such as oxides ( example, haematite, tin stone etc.), carbonates ( example, calamine, malachite, extra), native gold, etc.                                                                 The ore is washed with running water using big tubs or wilfley table that has sluices (grooves). The lighter impurities are washed away and the heavier particles of the ore settle down.                     
4. Froth Floatation Method:- This method is employed to purify/concentrate sulphide ores. This method uses: 

(a) Water.

(b) Pine oil or eucalyptus oil to produce foam and work as              collector / transforming agent.

(c) Cresols or aniline to stabilise foam.

(d) Xanthate (commonly employed xanthate is potassium ethyl xanthate collector to increase wetting of sulphide ore.

(e) Depressants and activators to collect the required sulphide part from the ore. For example, Galena contains a good quantity of ZnS with PbS into water soluble complex Na2[Zn(CN4)].  

The powered ore is put in a tank containing a stirrer, a device of passing compressed air and all the above material. Foam is produced by wetting and lifting of sulphide ore to the surface. It is washed with acidulated water to collect the ore.  
                                                                                              

 5. Leaching:- It is the method of collecting the required metal from an ore, in the form of aqueous solution of its selection compound, by treating the ore with acid or base or some other reagent. Leaching is often used if the ore is soluble in some suitable solvent.

Leaching of alumina from bauxite

In Bayer's process, for red bauxite, the ore is continuously stirred with 45% NaOH at 200-250°C to collect the solution of sodium meta aluminate NaAlO2 or Na[Al(OH)4]. It is then diluted and kept with Al(OH)3 (suds) for about 36 hours at 25-50°C to convert it to Al(OH)3(ppt). Ignition of Al(OH)3 at 1200°C produces Al2O3.

Al2O3.2H2O + 2NaOH -------> 2NaAlO2 + 3H2O  ( 45% NaOH {200-250°C})

NaAlO2 + H2O ------> Al(OH)3 + NaOH    ( AlOH3 {36 hours/25-30°C})

2Al(OH)3 ------> Al2O3 + 3H2O  ( 1200°C)

In serpeck's methods white bauxite is generally heated with coke in the presense of N2 gas. AlN produced is reacted with water to produce Al(OH)3 which on ignition gives Al2O3.

Al2O3 + N2 + 3C ------> 3CO + 2AlN  

                  heated

AlN + 3H2O ------> NH3 + Al(OH)3

  6. Conversion of Ore to Oxide Form: Sulphide ores thermodynamically more stable than CS2 and hence cannot be converted by using coke (general and common reducing agent) as reducing agent. Moreover CO2 is more volatile and thermodynamically more stable than CS2. This all means that ΔfG' of a metal sulphide is not compensated by the energy of reaction of metal sulphide with coke.

Hence, it is better to convert the sulphide ore to oxide form and then apply smelting, i.e., carbon reduction method.

• Calcination:- Conversion of hydrated oxides, carbonates, basic carbonates and hydroxide ores to their oxides by heating in the absence of O2 below their melting point is known as calcination.

Calcination makes the oxides porous thus increasing the surface area for further reaction.

Fe2O3.xH2O(s)  ----->   Fe2O3(s)  +   xH2O(g)

limonite       heated   ferric oxide

ZnCO3(s)   ----->   ZnO(s)  +   CO2(g)

calamine    heated     zinc oxide  

CaCO3        ----->   CaO       +     CO2

lime stone     heated    calcium oxide

•  Roasting:- In roasting, the ore is heated in a regular supply of air in a furnace at a temperature below the melting point of the metal.

(a) Oxidising Roasting:- It is done to remove Sulphur(S), Arsenic(As), Antimony(Sb), Phosphorous(P) in the form of their oxides.

S + O2  ------> SO2

sulphur            sulphur dioxide

As + O2  ------> As2O3

arsenic             arsenic oxide

P   +  O2  -----> P4O10

phosphorous          phosphorous pentoxide

       Sulphide ore of lead(Pb), Zinc(Zn), Nickel(Ni), Copper(Cu) etc are roasted by this method.

2PbS + 3O2 ------> 2PbO + SO2

ZnS + O2  ------> ZnO + SO2

FeS + O2 ------> FeO + SO2

Cu2S + O2  ----> FeO + SO2

(b)  Sulphating:- when oxidising roasting is done at moderate temperature apart of sulphide ore is oxidised to oxide and another part to sulphate.

PbS + O2 ----> PbO +SO2

PbS + O2 ----> PbSO4   (at moderate temperature)

ZnS + O2 -----> ZnO + SO2

Zns + O2 ----> ZnSO4  (at moderate temperature)

(c) Chlorinating:- If extraction of metal is difficult from its oxide in such cases metal is obtained by reduction of its chloride.

Ag2S      +    2NaCl   ---->   2AgCl   +   Na2S

silver galance

7. Reduction of Oxide to metal:

• Smelting:- The process of extraction of metal in few states [Fe(iron), Cu(copper) etc] or in gaseous state [Zn(zinc)] is called smelting. For the extraction of less electro-positive metals powerful reducing agent may be used.

IMPURITY + FLUX ---------> SLAG

FeO    +       SiO2        --------->       FeSiO3

impurity          acidic flux                          slag 

SiO2     +     CaO         --------->       CaSiO3

impurity         basic flux                          slag

• Reduction by C and CO (carbon reduction method):- Metals which are less electro-positive and do not form carbites with carbon are reduced by this method.

In this process ore is strongly heated with coke or coal in blast furnace where metal is obtained in the form of vapours in molten state.

C + O2   ---->   2CO

        900-1500K

FeO + CO   ---->   Fe + CO2

          900-1500K

ZnO +C   ----->   Zn   +   CO

        1120-1323K

NiO   +   C  -----> Ni  +  CO

NOTE:- Below and at 710°C (CO) is best reducing agent while above 710°C (C) is best reducing agent.

• Reduction by metals:- Highly electro-positive metals (like Na, K, Li, Al etc) are used to reduce the less electro-positive metals (like Cr, Cu, Mn etc).

(a) Kroll's process for titanium

TiCl4 + 2Mg ----> 2MgCl2 + Ti

(b) Gold Schmidt alumino thermite process

Oxides of maganese, chromium, iron, etc. can be reduced by using aluminium powder as reducing agent. A mixture of BaO2 and Mg is used as ignition mixture to supply heat.

3Mn3O4 + 8Al ----> 4Al2O3 + 9Mn

• Reduction by Hydrogen or Water gas:- Though, the use of H2 is expensive and not very safe, Yet H2 is used as reducing agent when carbon becomes ineffective for reduction.

CuO + H2 ----> Cu + H2O

VO3 + H2 ----> V + H2O

NiO + CO + H2 ----> Ni + CO2 + H2O

Ag2O + H2 ----> Ag + H2O

It is used for less electro-positive metals.

• Self reduction or Auto reduction:- Sulphide ores of less electro-positive metals like Hg, Pb, Cu, etc are heated in air as to convert part of the ore into oxide or sulphate which then reacts with the remaining sulphide ore to give the metal and sulphur dioxide. No external reducing agent is used in this process.

2HgS + 3O2 ----> 2HgO + 2SO2

cinnabar

HgO + HgS ----> Hg + SO2

PbS + O2 ----> PbO + SO2

galena

PbO + PbS ----> Pb + SO2

• Amalgumetion:- This process is used for extraction of noble metals like Platinum, Gold, Silver etc.

METAL + Hg ----> AMALGAM ----> Hg(v) + METAL

                         dist.          pure