{"id":19569,"date":"2022-12-01T10:00:52","date_gmt":"2022-12-01T04:30:52","guid":{"rendered":"https:\/\/www.aplustopper.com\/?p=19569"},"modified":"2022-12-02T09:18:33","modified_gmt":"2022-12-02T03:48:33","slug":"cbse-class-10-science-lab-manual-types-reactions","status":"publish","type":"post","link":"https:\/\/www.aplustopper.com\/cbse-class-10-science-lab-manual-types-reactions\/","title":{"rendered":"CBSE Class 10 Science Lab Manual – Types of Reactions"},"content":{"rendered":"

CBSE Class 10 Science Lab Manual – Types of Reactions<\/strong><\/span><\/h2>\n

EXPERIMENT 3(a)<\/strong><\/span><\/p>\n

Aim<\/strong><\/span>
\nTo perform and observe the action of water on quicklime, action of heat on ferrous sulphate crystals, reaction of iron nails kept in copper sulphate solution, reaction between sodium sulphate and barium chloride solutions and classify the reaction.<\/p>\n

Materials Required<\/strong><\/span>
\nCalcium oxide (quicklime), distilled water, borosil beaker, test tube, glass rod, dropper, red and blue litmus paper strips.<\/p>\n

Theory<\/strong><\/span>
\nWhen calcium oxide (quicklime) is dissolved in water, it forms calcium hydroxide (slaked lime). The reaction is highly exothermic, i.e. a lot of heat is produced during the reaction.
\nThis reaction may be represented in the form of a chemical reaction as follows:
\n\"CBSE
\nNote Calcium hydroxide is basic in nature.
\nTherefore, it turns moist red litmus paper blue. If we pass CO2<\/sub> through clear calcium hydroxide solution (lime water), it turns milky due to the formation of a white precipitate (insoluble calcium carbonate).
\n\"CBSE
\nIn reaction (i), two compounds-quicklime and water combine to give a single product slaked lime. So, this is an example of combination reaction. Hence, it may be stated that when two or more substances react together to form a single product, is called a combination reaction.
\nAlso, it has been observed that a large amount of heat is evolved alongwith the formation of products. Such type of reactions which are accompanied by the evolution of heat, are called exothermic reactions.<\/p>\n

Procedure<\/strong><\/span><\/p>\n

    \n
  1. Take a small amount of quicklime in a borosil beaker or hard glass beaker. Slowly add water to it as shown in Fig. 1 (a).<\/li>\n
  2. Stir it well with a clean glass rod as shown in Fig. 1(b).
    \n\"CBSE<\/li>\n
  3. Observe what happens. Touch the beaker carefully.<\/li>\n
  4. Classify the reaction.<\/li>\n
  5. Using a clean dropper, take a few drops of the solution formed in the beaker and place them on red and blue litmus paper strip (as shown in Fig. 2). Make your observation.
    \n\"CBSE<\/li>\n<\/ol>\n

    Observation<\/strong><\/span>
    \nThe hissing sound is produced and solution becomes hot. The heat is evolved during the reaction which raises the temperature of the reaction mixture. On putting a few drops of the solution on red and blue litmus paper, it is observed that only red litmus paper turns blue, no changes occur in blue litmus paper.<\/p>\n

    Inference<\/strong><\/span>
    \nIn this reaction, quicklime (CaO) and water (H2<\/sub>O) combine to give a single product slaked lime [Ca(OH)2<\/sub> ].
    \nCaO(s) + H2<\/sub>O (l) ——–> Ca(OH)2<\/sub> (aq) + Heat
    \nIt is a combination reaction and calcium hydroxide [Ca(OH)2<\/sub> ] is basic in nature.
    \nAs heat is evolved, the reaction is exothermic.<\/p>\n

    Result<\/strong><\/span>
    \nThe reaction between quicklime and water to form slaked lime is a combination reaction as well as exothermic reaction.<\/p>\n

    Precautions<\/strong><\/span><\/p>\n

      \n
    1. Always take small amount of quicklime.<\/li>\n
    2. The reaction is highly exothermic, so do not touch the reaction mixture directly.<\/li>\n
    3. Water is added slowly to a beaker containing quicklime.<\/li>\n
    4. Quicklime can cause severe burns, therefore, it should be handled with spatula.<\/li>\n
    5. Use good quality glassware, while adding water to quicklime. This is because, the reaction is highly exothermic and the beaker if made of ordinary glass, can crack.<\/li>\n<\/ol>\n

      Viva – Voce<\/strong><\/span><\/p>\n

      Question 1.<\/span><\/strong>
      \nWhat is combination reaction?
      \nAnswer:<\/strong><\/span>
      \nA reaction in which two or more substances combine to form a single product (compound) is called a combination reaction.<\/p>\n

      Question 2.<\/span><\/strong>
      \nWhat is calcium oxide commonly called?
      \nAnswer:<\/strong><\/span>
      \nCalcium oxide (CaO) commonly known as quicklime.<\/p>\n

      Question 3.<\/span><\/strong>
      \nWhen slaked lime is brought in contact with red litmus paper, what do you observe?
      \nAnswer:<\/strong><\/span>
      \nWe observe that red litmus paper turns blue. From this, we can conclude that slaked lime is basic in nature.<\/p>\n

      Question 4.<\/span><\/strong>
      \nA small amount of quicklime is taken in a beaker. Water is added slowly to the beaker. What observation would you note down?
      \nAnswer:<\/strong><\/span>
      \nWhen water is added slowly in a quicklime, hissing sound is produced and the solution becomes hot.<\/p>\n

      Question 5.<\/span><\/strong>
      \nName the reaction between calcium oxide and water.
      \nAnswer:<\/strong><\/span>
      \nThe reaction between calcium oxide and water is known as combination reaction.<\/p>\n

      Question 6.<\/span><\/strong>
      \nWhy should we not touch iron container in which CaO reacts with H2<\/sub>O?
      \nAnswer:<\/strong><\/span>
      \nWe should not touch iron container in which CaO reacts with H20 because iron container will be very hot as the reaction is exothermic.<\/p>\n

      Question 7.<\/span><\/strong>
      \nWrite the product formed when quicklime reacts with water.
      \nAnswer:<\/strong><\/span>
      \nQuicklime reacts with water to give calcium hydroxide Ca(OH)2<\/sub>, ie. slaked lime.
      \nCaO+ H2<\/sub>O ——–> Ca(OH)2<\/sub><\/p>\n

      Question 8.<\/span><\/strong>
      \nWhat is the effect of temperature on the solubility of calcium hydroxide?
      \nAnswer:<\/strong><\/span>
      \nSolubility of calcium hydroxide or slaked lime decreases with increase in temperature.<\/p>\n

      Question 9.<\/span><\/strong>
      \nIs the reaction between quicklime and water exothermic or endothermic?
      \nAnswer:<\/strong><\/span>
      \nAs heat energy is released during the reaction, therefore it is an exothermic reaction.<\/p>\n

      Question 10.<\/span><\/strong>
      \nName the chemical formula and chemical name of slaked lime.
      \nAnswer:<\/strong><\/span>
      \nChemical formula of slaked lime \u2014 Ca(OH)2<\/sub>
      \nChemical name of slaked lime \u2014 Calcium hydroxide<\/p>\n

      Question 11.<\/span><\/strong>
      \nMost of the combination reactions are exothermic in nature. Give reason.
      \nAnswer:<\/strong><\/span>
      \nMost of the combination reactions are accompanied by liberation of heat energy. This is known as exothermicity. For example, when natural gas burns in the oxygen of air, it forms carbon dioxide and water vapour. A large amount of heat is also produced.
      \n\"CBSE<\/p>\n

      Question 12.<\/span><\/strong>
      \nGive an example of a combination reaction.
      \nAnswer:<\/strong><\/span>
      \nWhen magnesium ribbon burns in air, it forms magnesium oxide. This is an example of combination reaction.
      \n\"CBSE<\/p>\n

      Question 13.<\/span><\/strong>
      \nHow is lime water prepared?
      \nAnswer:<\/strong><\/span>
      \nMix calcium oxide with water, shake the mixture well and leave it to stand for a while. Collect the clean solution on top. This is lime water.<\/p>\n

      Question 14.<\/span><\/strong>
      \nWhat is the suspension of slaked lime in water commonly called?
      \nAnswer:<\/strong><\/span>
      \nThe suspension of slaked lime in water is commonly called milk of lime.<\/p>\n

      Question 15.<\/span><\/strong>
      \nWhy lime water turns milky when CO2<\/sub> gas is passed through a test tube containing lime water?
      \nAnswer:<\/strong><\/span>
      \nLime water turns milky due to the formation of insoluble precipitate of calcium carbonate (CaCO3<\/sub>).<\/p>\n

      Question 16.<\/span><\/strong>
      \nAvinav takes 2 mL of clear liquid from the mixture of quicklime with water and then he breath out in it. What would he observed?
      \nAnswer:<\/strong><\/span>
      \nThe filtrate turns milky.<\/p>\n

      Question 17.<\/span><\/strong>
      \nOut of CuO, Na2<\/sub>O, CaO and P2<\/sub>O5<\/sub>, in which oxide solution, lime water is formed when water is mixed?
      \nAnswer:<\/strong><\/span>
      \nWhen water is mixed with CaO, lime water is formed<\/p>\n

      EXPERIMENT 3(b)<\/strong><\/span><\/p>\n

      Materials Required<\/strong><\/span>
      \nFerrous sulphate crystals (2g), boiling tube, test tube holder, safety glass (goggle), Bunsen burner, blue and red litmus paper strips.<\/p>\n

      Theory<\/strong><\/span>
      \nThe ferrous sulphate crystals are actually ferrous sulphate heptahydrate (FeSO4<\/sub>.7H2<\/sub>O). They contain seven molecules of water of crystallisation. These crystals are green in colour.
      \nHeating of Ferrous Sulphate Crystals<\/strong>
      \nWhen the green coloured ferrous sulphate heptahydrate crystals (FeSO4<\/sub>.7H2<\/sub>O) are heated, they first lose seven molecules of water of crystallisation to form anhydrous ferrous sulphate (FeSO4<\/sub> ) which is white in colour.
      \nWhen this anhydrous ferrous sulphate is heated, it decomposes to give ferric oxide, sulphur dioxide and sulphur trioxide.
      \nThe reactions may be represented as:
      \n\"CBSE
      \nIn this reaction, one substance FeSO4<\/sub>(s) is splitting up into three substances Fe2<\/sub>O3<\/sub>(s), SO2<\/sub>(g), SO3<\/sub>(g) because it takes place due to heat.
      \nSo, this is a decomposition reaction. It is actually a thermal decomposition reaction.
      \nOn combining Eqs. (i) and (ii), we can write the reaction as:
      \n\"CBSE<\/p>\n

      Procedure<\/strong><\/span><\/p>\n

        \n
      1. Take about 2g ferrous sulphate crystals in a boiling tube.<\/li>\n
      2. Note the colour of ferrous sulphate crystals.<\/li>\n
      3. Hold the boiling tube in a test tube holder.<\/li>\n
      4. Heat the boiling tube (as shown in Fig. 1) and observe the odour of gases evolved and colour of residue formed.
        \n\"CBSE<\/li>\n
      5. Steamy fumes are given out which condense to form tiny droplets of a colourless liquid at the neck of boiling tube. Test the nature of these droplets with the help of blue and red litmus paper.<\/li>\n
      6. Smell if any gas evolved by turning it gently towards your nose with a blow of your hand (as shown in Fig. 2).
        \n\"CBSE<\/li>\n
      7. Bring a wet blue and red litmus paper near the mouth of the boiling tube (as shown in Fig. 3) and observe the change.
        \n\"CBSE<\/li>\n
      8. Classify the reaction.<\/li>\n<\/ol>\n

        Observation<\/strong><\/span><\/p>\n

          \n
        1. The green colour of ferrous sulphate crystals first changes to white and then a brown solid is formed (which is ferric oxide, Fe2<\/sub>O3<\/sub>).<\/li>\n
        2. Both red and blue litmus paper do not show any change in colour with tiny droplets, formed at the neck of boiling tube.<\/li>\n
        3. Gas having the smell of burning sulphur comes out of the boiling tube.<\/li>\n
        4. Moist blue litmus paper turns red when it comes in contact with evolved gas.<\/li>\n<\/ol>\n

          Inference<\/strong><\/span><\/p>\n