Description : What happens when? a) A cleaned iron plate or iron nail is kept in 10g of copper sulphate solution. b) A pinch of mercuric oxide is kept in a test tube. c)A small crystal of silver nitrate is dissolved in distilled water and a drop of ammonium hydroxide & a pinch of glucose powder are added.
Last Answer : a) A cleaned iron plate or iron nail is kept in 10g of copper sulphate solution. After a few hours a coating of copper is seen on iron nail/plate. It is based on displacement reaction. ... on the inner walls of the test tube. Aldehyde group in glucose reduced silver nitrate to metallic silver.
Description : What happens when a iron nail or a piece of aluminium wire is dipped in concentrated nitric acid?
Last Answer : Iron nail or aluminium wire does not react with concentrated nitric acid. It makes iron more passive.
Description : A student has been collecting silver coins and copper coins. One day she observes a black coating on silver coins and a green coating on copper coins. Which chemical phenomenon is responsible for these coatings? Write the names of black and green coatings.
Last Answer : The phenomenon is called corrosion. Silver gets tarnished when exposed to atmosphere which forms a black coating of silver oxide. Copper forms a green deposit on its surface when exposed to moist air. The green coating is copper sulphate.
Description : Give reason: Some metals are more reactive than others.
Last Answer : Metals are electropositive and have tendency to donate electrons. Some elements give up their valence electrons and hence more reactive.
Description : Give reason: Iron displaces copper from copper sulphate solution.
Last Answer : Iron is more reactive than copper. Hence it displaces copper from copper sulphate solution.
Description : 10.(a) An ore on treatment with dilute hydrochloric acid produces brisk effervesces. What type of ore is this? What steps will be required to obtain metal from the enriched ore. , (b) ... in coin and colour of the solution ? Write balanced chemical equation of the reaction involved. -Chemistry
Last Answer : (a) Carbonate ore: (i) Calcination: Carbonate ore is heated in limited supply of air and oxide is obtained, e.g. (b) Copper, being more reactive than silver will displace silver from silver nitrate ... and there will be deposition of silver on copper coin. The colour of solution will turn to blue.
Description : Give reason: a) Magnesium reacts more vigorously with hydrochloric acid than zinc or copper. b) Iron takes more time to react with dilute hydrochloric acid than magnesium and zinc
Last Answer : a) Magnesium reacts more vigorously with hydrochloric acid than zinc or copper. The reactivity of magnesium is higher than that of zinc. Hence it reacts with hydrochloric acid more vigorously. b) ... acid than magnesium and zinc As iron has lowest reactivity when compare to magnesium and zinc.
Description : Why is 6% to 8% copper added to gold in making ornaments?
Last Answer : Pure gold is very soft, it cannot be used to make artistic ornaments. To make it hard, improve the looks and colour, 6 to8% copper is added to ornamental gold.
Description : Briefly explain the electrolytic refining of copper.
Last Answer : Copper is purified by electrolytic refining. The apparatus consists of an electrolytic tank containing copper sulphate solution as electrolyte. A set of thick blocks of impure copper is made anode ... anode becomes thinner and pure cathode becomes thicker. The impurities collect at the bottom.
Description : Sodium displaces hydrogen from dilute acids violently but copper does not displace hydrogen from dilute acids. Why?
Last Answer : Sodium is highly reactive than copper. Hence reaction with sodium reacts violently then that of copper.
Description : Which property of copper and aluminium makes them suitable?
Last Answer : a) For making cooking utensils and boilers. Good conductor of heat. b) For making electric wires. Good conductor of electricity.
Description : Which metal is present both in brass and bronze?
Last Answer : Copper
Description : Explain the process of zone refining. Name one metal refined by this method.
Last Answer : The apparatus used for zone refining consists of a circular heater fitted around the rod of impure metal at one end. The circular heater is slowly moved to the other end. At the heated zone, ... in solid metal passes into the adjacent molten part. A metal refined by zone refining is germanium.
Description : Mention the methods of obtaining ultra pure metal.
Last Answer : a) Fractional crystallization or zone refining. b) Vacuum melting c) Distillation d) Chemical vapour deposition e) Liquation process
Description : Which gas is always produced if a metal reacts with water or dilute acid?
Last Answer : Hydrogen
Description : Petrol is not selected for preserving sodium or potassium metal. Why?
Last Answer : Petrol evaporates easily and is costly hence kerosene is used.
Description : Give reason: a) Metals are electropositive. b) Non-metals are electronegative. c) Even though hydrogen is a non-metal, it is electropositive. d) Sodium is electropositive.
Last Answer : a) Metals are electropositive. Electropositive element has the tendency to lose electrons and form cation.Metals are electron donors. Hence they are electropositive. b) Non-metals are ... is electropositive because donates electrons from last orbit to another element and becomes electropositive.
Description : (a) Write one example for each of decomposion reaction carried out with help of (i) Electricity (ii) Heat (iii) Light (b) Which of the following statements is correct and why copper can displace silver from silver nitrate and silver can displace copper from copper sulphate solution. -Chemistry
Last Answer : Thi is the Answer:
Description : Why do gold ornaments look new even after several years of use?
Last Answer : Gold does not corrode when exposed to atmosphere. It is a highly unreactive metal and is unaffected by air, water vapour and other gases in atmosphere.
Description : A metal salt solution gives a yellow precipitate with silver nitrate. The precipitate dissolves in dilute nitric acid as well as in ammonium hydroxide
Last Answer : A metal salt solution gives a yellow precipitate with silver nitrate. The precipitate dissolves in dilute nitric acid as ... (3-)` D. `SO_(4)^(2-)`
Description : Give reason: Metallic articles which are exposed to air over long period of time lose their lustre.
Last Answer : Due to the formation of oxide, hydroxide and carbonate layers.
Description : Name some metals which do not displace hydrogen from dilute acids.
Last Answer : Platinum, gold, silver, mercury & copper do not displace hydrogen from dilute acids.
Description : An iron nail is dipped in the solution of copper sulphate for about 30 minutes. State the change in colour observed. Give reason for the change. -Chemistry-10
Last Answer : When an iron nail is dipped in copper sulphate solution, the displacement reaction takes place. The colour of copper sulphate solution fades due to the formation of light green solution of iron sulphate.
Description : Why does the colour of copper sulphate solution change when an iron nail is dipped in it ? -Chemistry-10
Description : Why does the colour of copper sulphate solution change when an iron nail is dipped in it? Write two observations. -Chemistry
Last Answer : Answer. It is because displacement reaction takes place. Iron displaces copper from copper sulphate solution and forms pale green coloured solution of FeS04 and reddish brown copper metal gets deposited. Fe(s) + CuS04(aq) ——–> FeS04(aq) + Cu(s)
Description : What happens when zinc is dipped in a copper sulfate solution Zinc is higher on the activity series than copper.?
Last Answer : Zinc becomes plated with copper.
Description : science Topic : Metals Fill in the blanks.
Last Answer : 1. An example of a liquid metal is Mercury/gallium. 2. A metal which is soft is sodium. 3. A metal which lacks ductility is sodium. 4. A non-metal which is lustrous is graphite/iodine ... 59. Aluminium+ copper+ magnesium+ manganese is useful in making aircraft bodies. 60. Ornamental gold is an alloy
Description : What are memory alloys? How are they useful?
Last Answer : Certain alloys which regain their original shape when deformed are called memory alloys. Preparation of memory alloys saves energy of melting and recasting of used articles.
Description : Write a note on contributions of Indians to metallurgy.
Last Answer : a) Romans used armour and cutlery made from Indian iron. b) Indian metallurgist Nagarjuna wrote the book Rasaratnakara' in 9th century BC which explained the preparation of various metallic ... near Qutab Minar constructed by Vikramadithya about 1600 years ago has withstood the action of weather.
Description : What property of invar steel is used in making pendulums and measuring tapes?
Last Answer : Invar steel has the least co-efficient of linear expansion.
Description : What property of stainless steel is used in making surgical instruments?
Last Answer : Surgical steel is not attacked by mild chemicals easily and it does not corrode.
Description : How are the properties of alloys different from those of metals?
Last Answer : Copper is reddish and zinc is grayish in colour where as brass which is an alloy of copper and zinc is golden yellow in colour. Iron is a magnetic substance but stainless steel, an alloy of iron is non magnetic.
Description : Give reason: Metals belonging to the same group form good alloys.
Last Answer : As metals belonging to the same group in the periodic table have similarities in electronic configuration.
Description : Why are alloys made?
Last Answer : Alloys give desired properties to the metal. It improves the properties of metals.
Description : How is an alloy formed?
Last Answer : Alloysare prepared by mixing the various metals in their molten state and cool them to room temperature. Better quality can be made by mixing metals using ultrasonics.
Description : What is an alloy?
Last Answer : An alloy is a homogenous mixture of two or more metals or metal with a non-metal. Example: Brass is an alloy of two metals copper and zinc. Steel is an alloy of a metal iron and non-metal carbon.
Description : What is electrolytic refining?
Last Answer : Electrolytic refining is a technique of ultra refining of metal. In this method, impure metal is taken as anode and pure metal are taken as cathode. Electric current is passed through the electrolyte to obtain pure metal at the cathode.
Description : What is meant by zone refining or fractional crystallization?
Last Answer : Zone refining is a technique of obtaining ultra pure metal. It is based on the principle of differences in solubility of impurities in liquid and solid states of the metal.
Description : What is meant by liquation process?
Last Answer : Liquation is a process of obtaining ultra pure metal. It is based on the principle that metals are readily fusible where as the impurities are infusible at the temperature at which the metals fuse.
Description : Name the process by which the refining of aluminium is done. Name the material used for the process.
Last Answer : Aluminium is refined by electrolytic refining. Carbon lining acts as the cathode and the graphite rods act as anode.
Description : Briefly explain the extraction of aluminium from alumina with chemical equations.
Last Answer : Aluminium oxide dissolved in molten cryolite is taken in a chamber with gently sloped base.The inner wall is made of carbon lining. Graphite rods are introduced in the electrolyte bath. The carbon lining ... is passed. Molten aluminium collects at the lining and flows out of the gently sloped base.
Description : What is cryolite? Write its chemical formula.
Last Answer : Cryolite is chemically sodium aluminium fluoride. Its molecular formula is Na3AlF6.
Description : What is the role of molten cryolite in the extraction of aluminium?
Last Answer : When pure alumina is mixed with molten cryolite, it forms an electrolyte at 1223K. Molten cryolite also acts as a solvent for alumina.
Description : What is the difficulty in obtaining aluminium from alumina?
Last Answer : Pure alumina melts at 2323K. At this temperature, aluminium vapourises and there will be considerable loss. It consumes more energy and also molten aluminium is not a very good conductor of electricity.
Description : Why is pure alumina needed for the extraction of aluminium?
Last Answer : For electrolysis of we need pure alumina. Hence bauxite is converted into alumina by chemical process.
Description : Why is extraction of aluminium not commercially viable by using reducing agents like coke? OR Coke is used in the extraction of iron but not in the extraction of aluminium. Why? OR Aluminium cannot be extracted by heating bauxite and coke. Why?
Last Answer : Oxygen of aluminium oxide cannot be easily taken away by reducing agents like coke.
Description : What is alumina? Write its molecular formula.
Last Answer : Alumina is chemically hydrated oxide of aluminium. Its formula is Al2O3.2H2O.
Description : What is a mordant?
Last Answer : A mordant is a substance which helps to bind the dye to the cloth.
Description : Mention the uses of aluminium salts.
Last Answer : a) Aluminium salts are used as mordant in textile industry (to bind the dye to the cloth). b) Potash alum is used to prevent bleeding from small cuts by coagulating the blood at the surface.
Description : Name the impurities present in cast iron. How can these impurities be removed?
Last Answer : Cast iron contains sulphur, phosphorous, silicon and carbon. The impurities present in the blast furnace can be removed by using Bessemer converter, open hearth process or electric furnace.