PRECAUTIONS WHILE PERFORMING CHEMISTRY ACTIVITIES. Do not touch anything without the permission of the teacherin the lab.

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1 PRECAUTIONS WHILE PERFORMING CHEMISTRY ACTIVITIES Do not touch anything without the permission of the teacherin the lab. 1. Do not use conc. Acids as they are harmful. 2. Handle glass material with care. 3 Never smell a gas directly. 4. Perform all the activities under the observation of teacher. 5. Keep all the chemicals away from the burner.

2 To show the characteristics of a chemical reaction Take few zinc granulesin a conical flask or a test tube. Add dilute hydrochloric acid or sulphuric acid to this. we observe a brisk effervescense. Touch the conical flask or test tube the flask becomes hot. Conclusion- The chemical reaction may be characterized by evolution of a gas, change in energy, change in colour or formation of precipitate. 2.To show combination reaction of CaO with water. 1.Take a small amount of calcium oxide or quick lime in a beaker. 2.Slowly add water to this. 3.Touch the beaker the beaker becomes hot as a large amount of heat is evolved. Conclusion-The reaction of calcium oxide with water is exothermic. 3. Action of heat on FeSo 4 crystals. 1.Take about 2g ferrous sulphate crystals in a dry boiling tube. 2. Note the colour of the ferrous sulphate crystals. Heat the boiling tube over the flame of a burner or spirit lamp. Observe the colour of the crystals after heating.the colour becomes white. Conclusion-Ferrous sulphate on heating gives out water of crystallization and becomes anhydrous. 4. Action of sunlight on AgCl. Take about 2g of silver chloride in a china dish. Place this china dish in sunlight for some time. Observe the colour of silver chloride after some time. Conclusion-On exposing AgCl to sunlight decomposition reaction takes place and silver chloride breaks down to produce silver and chlorine gas is released.

3 5.Reaction of iron nails with copper sulphate solution. Take three iron nails and clean them by rubbing sand paper. Take 2 test tubes marked as (A) and (B). In each test tube, take about 10 ml copper sulphate solution. Tie two iron nails with a thread and immerse them carefully in a copper sulphate solution in test tube (B) for about 20 mins. Keep one iron nail aside for comparison. After 20 mins. take out the iron nails from the copper sulphate solution. Compare the intensity of the blue colour of the copper sulphate in test tubes (A) and (B). Also compare the colour of iron nails dipped in the copper sulphate solution. Conclusion-Since iron is more reactive than copper it displaces copper from copper sulphate. The blue colour of copper sulphate changes to green because of formation of ferrous sulphate and reddish brown deposit of copper is formed over iron nails.the intensity of blue colour in test tube (B) is less. 6.Reaction of Na2 SO4 and BaCl2 Take about 3ml of sodium sulphate solution in a test tube. In another test tube. Take about 3ml of barium chloride solution. Mix the two solutions A white precipitate is formed. Conclusion- This is an example of double decomposition reaction in which barium sulphate forms a precipitate. 7. To show the oxidation of copper. Heat a china dish containing about 1g of copper powder. Copper combines with oxygen to form copper oxide which is black in colour. Conclusion- This is an example of combination reaction 8. Reaction between PbNO3 and KI Take lead nitrate solution in a test tube. Add potassium iodide solution to this. Yellow precipitate is formed Conclusion-The reaction is an example of double decomposition reaction in which lead iodide forms a yellow precipitate.

4 Acid,Bases and salts. 1.To study properties of acid and bases by their actionwithlitmus ( red and blue) paper, phenolphthalein solution andmethyl orange. Collect hydrochloric acid, sulphuric acid, nitric acid, acetic acid, sodium hydroxide calcium hydroxide, potassium hydroxide, magnesium hydroxide and ammonium hydroxide. put a drop of each of above solutions on a watch-glass and test with a drop of the following indicators. what change in colour do you observe with red litmus,blue litmus, phenolphthalein and methyl orange solutions for each of the solutions taken. Conclusion- acids change blue litmus red,bases red litmus blue,bases change phenolphthalein solution to pink. 2.Reaction of Zinc granules with dilute H2SO4 and testing H2 gas by burning. Take about 5ml of dilute sulphuric acid in a test tube and add a few pieces of zinc granules to it. Test the gas evolved by bringing the burning splinter. Conclusion-The gas burns with a pop sound and puts off the burning splinter. The gas is hydrogen. 3.Passing of CO2 through Ca(OH)2 Take 2 test tubes. Label them as (A) and (B). Take about 0.5 g of sodium carbonate in test tube (A) and about 0.5 g of sodium hydrocarbonate in test tube(b). Add about 2ml of dilute HCl to both the test tubes. Pass the gas produced in each case through lime water. Conclusion-The gas produced is carbon dioxide which turns lime water milky. 4. Reaction between acid and base. Take about 2ml of dilute NaOH solution in a test tube and add two drops of phenolphthalein solution. The colour of solution becomes dark pink. Add dilute HCl to the above solution drop by drop. We observe that the solution becomes colourless. It is concluded that colour changes on addition of acid because base is neutralized by acid. Conclusion- If we add a drop of sodium hydroxide the pink colour re-appears because there is excess base in the solution.

5 5. Reaction of metallic oxides with acids. Take a small amount of copper oxide in a beaker and add dilute hydrochloric acid slowly while stirring. We observe that the colour of the solution becomes blue-green and the copper oxide dissolves. Conclusion- The blue-green colour of the solution is due to the formation of copper (ii) chloride in a reaction. 6. Dilution of acid. Take 10 ml of water in a beaker. Add a few drops of concentrated H2SO4 to it and swirl the beaker slowly. Touch the base of the beaker. We observe that the solution becomes warm. Conclusion- It is concluded that dilution of an acid is an exothermic reaction. 7.Testing the ph of soil. Put about 2g soil in a test tube and add 5ml of water to it. Shake the contents of the test tube. Filter the contents and collect the filtrate in a test tube. Check the ph of this filtrate with the help of universal indicator paper. 8.Heating of CuSO4 crystals water ofcrystallization. Heat a few crystals of copper sulphate in a dry boiling tube. We observe that the colour of the copper sulphate crystals becomes white. We notice water droplets in the boiling tube. Add 2-3 drops of water on the sample of coppersulphate obtained after heating. We observe that the blue colour of crystals re-stored. This shows that copper sulphate crystals which seems to be dry contain water of crystallization. When we heat the crystals,this water is removed and the salt turns white. If we moisten the crystals again with water the blue colour of crystals re- appears. Conclusion- on heating copper sulphate, water of crystallization is given out and the salt becomes white. When water is added crystals again becomes blue by absorbing water of crystallization.