Hack tech fact

 Order of the reaction :   1- It is the sum of powers of the concentrations in the rate law expression. 2- It is an experimentally determined value obtained from the rate of overall reaction. 3- It may be a whole number, a fraction, or zero. 4- It cannot be obtained from a balanced chemical equation. 5- The mechanism of a chemical reaction cannot be known from the order of the reaction. 6- It can change with the conditions, such as pressure, temperature and concentration.

Molecularity of reaction: 1- It is the number of reacting species undergoing simultaneous collisions in the reaction. 2- It is a theoretical concept which depends upon the rate determining step in the reaction mechanism. 3- It is always a whole number and never zero, and generally never exceed three. 4- It is obtained from a single balanced equation. 5- The reaction mechanism can be know from the molecularity of a reaction. 6- It is invariant for a reaction.

 Adsorption: 1- It is a surface phenomenon. 2- The concentration of the adsorbing substance (adsorbates) is higher at the surface (of adsorbent) than in the bulk. 3- It may be +ve or -ve depending on the larger or less concentrations of the adsorbed substance on the surface of the adsorbent. * When the concentration of adsorbates is more on the surface of the adsorbent than in the bulk it is called positive adsorption, on the other hand, when the concentration of adsorbates is less on the surface of the adsorbent than in the bulk, it is called negative adsorption. 4- It is a rapid process. 5- The rate of adsorption is rapid initially but decrease slowly. Examples:  Water is adsorbed by silica gel. Ammonia is absorbed by charcoal.

Absorption: 1- It is an interior or bulk phenomenon. 2- The concentration of absorbed substance is uniform throughout the absorbing substance. 3- it is neither +ve or -ve, it is uniform. 4- It is a slow process because of diffusion. 5- The rate of absorption is uniform throughout. Example:   Water is absorbed by anhydrous calcium chloride. Ammonia is absorbed by water. 

Minerals:        The naturally occurring materials found in the earth crust in which metals are present in the native form or in combined state along with other impurities are called minerals or natural substances in which metal or their compounds are found in the earth's crust are called minerals.

Diffusion 1- It occurs directly and does not require any semi-permeable membrane. 2- Both the molecules of solute and Solvent move from a higher concentration to lower concentration. 3- It is applicable to both gases and liquids. 4- It can not be stopped by applying external pressure.

Osmosis 1- It takes in the presence of a semi-permeable membrane. 2- Solvent molecules move from a solution of lower concentration to that of higher concentration. 3- It is restricted to solutions only. 4- Osmosis ceases when an external pressure is applied.

 Electrolytic conduction: 1- Current passes by the movement of free ions. 2- Transfer of matter takes place in form of ions. 3- Change in Chemical properties takes place due to decomposition of electrolyte. 4- Resistance decreases or conductance increases due to increase in temperature. It is because due to increase in temperature, the viscosity of the medium and degree of hydration of ions increase which increase the movement of ions.

Metallic conductions 1- Current passes by movement of free electrons.  2- No transfer of matter takes place.  3- No change in chemical properties takes place  4- Resistance increase or conductance decreases due to increase in temperature. It is because due to increase of temperature thermal motion of metal ions increase which result in hindrance of flow of electrons.  

Electrolytic refining : Metals having large positive electrode potentials are purified by this method. The Metals to be purified should have lower discharge potential than the impurities. For example, during the purification of Cu metal, impure metal is made anode, a piece of pure metal is made cathode and electrolysis is carried in an electrolytic bath containing acidified CuSO⁴ as electrolyte.

 Van Arkel method: This method is called the vapour phase refining in which metal is converted to a volatile stable compound without affecting the impurities. The volatile compound is then decomposed to give pure metal. In this method ultrapure metals are obtained. Titanium and zirconium are refined by this method.

 Electrolytic refining: Metals having large positive electrode potential are purified by this method. The metals to be purified should have lower discharge potential than the impurities. For example, during the purification of Cu metal, impure metal is made anode, a piece of pure metal is made cathode and electrolysis is carried in an electrolytic bath containing acidified CuSO⁴ as electrolyte.

Electrolytic cell: 1- It is a device which convert electrical energy to chemical energ y. 2- In this cell +ve electrode is anode involving oxidation and -ve electrode is cathode involving reduction reaction. 3- In this cell electrons enter the cell from cathode to anode. 4- In this cell, electrodes are placed in the electrolytic solution in one containers. Chemical reaction is non spontaneous I.e. it takes place only by the passage of electricity.

Zone refining or Fractional crystallisation: Metals in high purity can be obtained in this method which is based on the difference in solubility in the liquid and solid states of the metal, and that of impurity, Ge,Si, and Ga used as semi-conductors are refined by this method. Gallium arsenide and indium antimonide used as semi-conductors are also refined by this method. In this method, a circular heater is fitted around a rod of impure metal and slowly moved over the rod. At the heated zone, the rod melts and as the heater moves, pure metals crystallises while the impurities drain away to the other part. The heater may have to be moved from one end to the other end of the rod more than once.  

 How we can separate two sulphide ores by froth flotation process? Explain with an example. Ans.            Two sulphide ores can be separated by adjusting the proportion of oil in water or by using depressants. For example, if an ore contain ZnS and PbS, a depressants NaCN is added so that it forms a complex with ZnS and prevents it from coming to the fort. On  the other hand, PbS comes into the forth and get separated.

 Zone refining or Crystallisation: Metals in high purity can be obtained in this method which is based on the differences in solubility in the liquid and solid states of the metal, and that of impurity, Ge,Si and Ga used as semi-conductors are refined by this method. Gallium arsenide and indium antimonide used as semi-conductors are also refined by this method. In this method, a circular heater is fitted around a rod of impure metal and slowly moved over the rod. At the heated zone, the rod metals and as the heater moves, pure metals crystallises while the impurities drain away to the other part. The heater may have to be moved from one end to the other end of the rod more than once.

Nature of metal and it's ion :  The electrode potential depends on the tendency of the electrode to form ions. It is a fact that no two electrodes have the same electron structure and therefore, no two electrodes have the same tendency to release electrons forming ions, I.e., the same electrode potential. For example, sodium being extremely active, loses electrons readily and has, therefore, high electrode potential. Cooper on the other hand being less active has a lower electrode potential.

Liquation:  Impure metals in the form of ingots (blocks) are placed in upper part of a slanting hearth maintained at a temperature slightly above the melting point of metals. The pure metals melts and drains away while the impurities remain behind as dross in the hearth.  

 Physical methods of refining : Distillation-                  Volatile metals containing non volatile impurities or vice versa are purified by this method. For example, low boiling points metals such as Zn and Hg are distilled by this method leaving behind less volatile impurities. Zn and Hg vapours are collected and condensed to get solid Zn or Hg.

 Heat treatment of steel: The properties of steel are modified on heat treatment: (1) Annealing:    In this process, steel is heated to a bright red heat and cooled slowly. By annealing, steel becomes soft. (2) Hardening:   when steel is heated to a bright red heat and cooled suddenly by dipping in oil or water (quenching) hard and brittle steel is obtained. (3) Tempering:   When steel is heated to a temperature much below redness and cooled slowly, the steel obtained is neither so hard or so brittle. (4) Nitriding:   In this case the steel is heated in an atmosphere of ammonia so that the surface is coated with hard iron nitride.

L . D PROCESS   to manufacturer best quality Steel: This is one of the most modern process of manufacturing best quality of steel and is used by Rourkela steel plant. The name L.D. stands for Lizard Donawitz, the names of places in Austria where it is first generated. This process makes use of L.D. converter which resembles like a Bessember converter in shape and has no holes at the bottom. It is fed with molten cast iron from the blast furnace and pure oxygen gas at high pressure is passed into it cooled by water at it's upper part. The impurities are oxidised and from which are removed. Then some alloy elements are added to molten mass to obtain steel of desired composition.

Electric arc process: In the process the the furnace consist of steel container lined inside with dolomite or magnesite provided with movable and water jacked electrodes fitted from the roof or from the sides of the container. A mixture of cast iron ore and scrap steel is taken in the container. On striking the electric are between the electrodes, heat is produced and the mixture melts. The impurities such as Si,mn,S and p combine with the basic lining and slaged off. The steel obtained is free from sulphur and gas bubbles. Alloy steels with high melting points are obtained in this process. High grade steel is obtained by this process. Steel so obtained is used for making utensils, swords, girders, etc.

 Different forms of iron: Mainly there are three commercial forms of iron. These are discussed below: 1- Cast iron or pig iron: It contains about 2 to 5% of carbon along with other impurities such as S,Si,p,Mn etc. It used as sewage pipes and plates as it is resistance to corrosion. 2- Wrought iron:  It is the purest form of iron containing 0.25% of carbon. It is malleable can be easily welded. 3- Steel:  It contains about 0.25 to 2 % of carbon i.e, the carbon content of steel is more than that of wrought iron and less than that of cast iron.

Zinc Refining:  - The zinc obtained by the process is impure and contain largely cadmium along with it. The impure is zinc is Known as spelter. Pure Zn obtained by Fractional distillation were Cd being more volatile (b.pt 775°C) than Zn (b.pt 906°C) distills over leaving behind pure Zn.              Zn can also be purified by electrolytic method. In this method impure Zn is made anode, pure Zn plate is made cathode and ZnSO⁴ solution containing little sulphuric acid is used as electrolyte. On passing electricity pure Zn is deposited at the cathode.

Extraction of copper Copper is extracted from the non-sulphide ores such as Malachite, azurite, etc. Following steps are involved in the extraction process using non-sulphide ores. 1- Cruising of the ore to a fine powder. 2- Concentration by Gravity process. The  3- calcination  4- Smelting  5- Leaching process

Leaching process:  Copper can be extracted from the concentrated oxide or carbonated ore by leaching process. This concentrated ote is treated with dilute sulphuric acid when copper sulphate is obtained in solution. From this solution, metallic copper is precipitated with iron fillings or recovered by electrolysis using lead anodes and pure copper cathode.

 Electrometallurgy:  The process of extraction of electro positive metals or highly reactive metals such as Na , K, Mg Al are not possible by pyrrometallurgical process. Therefore, these are extracted by electrometallurgical process.                The process of extraction of electropositive metals or highly reactive metals from their fused salt by electrolysis is called Electrometallurgy.

Metallic character: The elements of group 15 are less metallic than group 14 elements. However, metallic character increases on moving down the group.  Reason: Due to the increased nuclear charge and higher electronegativity, the elements of the group 15 are less metallic than the corresponding elements of  group 14. As on moving down the group, atomic size increases and electronegativity increases the valence electrons become loosely held and are lost more readily. Therefore, on moving down the group metallic character increases. In this family, N and P are non metals, As and Sb are metalloids While Bi is a typical metal.

Allotropic forms of phosphorus Phosphorus is found in many allotropic forms. But the important things of allotropic phosphorus are   White or yellow phosphorus ,R phosphorus ,Black phosphorus White or yellow phosphorus: This is the most common variety of phosphorus and is very reactive. Pure from is white and on exposure to light it turns yellow due to the Formation of a thin of red coating on it's surface   

 Thermal and Electrical conductivities:  Both thermal and electrical and electrical conductivities of theses elements increase on moving down the group. It is because the delocalization of electrons increases from the nitrogen with a co ordination number of six. Thus , N and P are non conductor while Bi is a good conductor of electricity.