What is slaked lime, quick lime, lime water. What are their uses?

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Jasmine Grover

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Calcium Hydroxide

Slaked Lime (Calcium Hydroxide) is a white powdery substance made by adding water to quicklime.

  • It is an inorganic compound having the chemical formula Ca(OH)2. 
  • The chemical reaction between quicklime and water is exothermic, producing heat and resulting in slaked lime.
  • It is a white powder or a colourless crystal obtained by mixing calcium oxide with water.

Calcium Oxide

Quick Lime (Calcium Oxide) or CaO is a white or grayish-white powder produced by heating limestone to a high temperature.

  • It is highly reactive and readily reacts with water to form slaked lime.
  • It is made by the thermal decomposition of materials like limestone or seashells to above 825 °C.

Lime Water

Lime Water is a solution of Calcium Hydroxide (slaked lime) in water. It is commonly used to test for carbon dioxide in gases and liquids.

Lime Cycle

Uses

The uses of slaked lime, quick lime, and lime water are as follows – 

Slaked Lime

  • In construction, slaked lime is used in making mortar and plaster.
  • It is also used in water treatment to adjust the pH and remove impurities.

Quick Lime

  • In the iron and steel industry, quick lime is used as a flux for removing impurities.
  • It is used for medicinal purposes and in insecticides.
  • The sugar industry uses quick lime to clarify sugar cane juice.
  • Lime is used in laboratories as a reagent for dehydration, precipitation, etc.

Lime Water

  • Lime water is used in the production of precipitated calcium carbonate (PCC), a commonly used filler in the paper, paint, and plastic industries.
  • Lime water is also used in the medical field as an antacid to neutralize excess acid in the stomach.

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CBSE CLASS XII Related Questions

  • 1.

    (i) Why do Zr and Hf exhibit similar properties ?

    (ii) "\( E^\circ \) for \( \mathrm{Mn^{3+}/Mn^{2+}} \) couple is more positive than that for \( \mathrm{Fe^{3+}/Fe^{2+}} \)." Justify the statement.

    [Atomic number : Mn = 25, Fe = 26]


      • 2.
        From the given data of \(E^{\circ}\) values, answer the following questions :
        (I) Why \(E^{\circ}_{M^{2+}/M}\) show irregular trend in the above values ?
        (II) Why is \(E^{\circ}_{Cu^{2+}/Cu}\) value exceptionally positive ?
        (III) Why \(E^{\circ}_{Mn^{2+}/Mn}\) value is highly negative ?


          • 3.

            (i) A first order reaction is 20% complete in 10 minutes. Calculate the time taken when 80% of the reaction will be completed.

            [Given : log 5 = 0.7, log 4 = 0.6]

            (ii) For a chemical reaction \( \mathrm{R \rightarrow P} \), variation in \( \ln[\mathrm{R}] \) vs. time (t) graph is given below :

            (I) Predict the order of the reaction.

            (II) Write the slope of the curve.




              • 4.
                Draw the structure of 'X' in the following reaction:


                  • 5.

                    A reaction \( \mathrm{A \rightarrow B} \) follows second order kinetics. How will the rate of reaction be affected if the concentration of (i) A is increased by three times, and (ii) A is reduced to half ?


                      • 6.
                        Consider the decomposition of hydrogen peroxide \( (\mathrm{H_2O_2}) \) as per the equation given below : \[ 2\mathrm{H_2O_2} \xrightarrow[\text{Alkaline medium}]{I^-} 2\mathrm{H_2O} + \mathrm{O_2} \] The mechanism for this reaction was found to be : Step I : \( \mathrm{H_2O_2} + I^- \longrightarrow \mathrm{H_2O} + IO^- \) (slow) Step II : \( \mathrm{H_2O_2} + IO^- \longrightarrow \mathrm{H_2O} + I^- + \mathrm{O_2} \) (fast) (a) Write the rate law expression. (b) Determine the order of reaction with respect to \( \mathrm{H_2O_2} \), \( I^- \) and overall order of reaction. (c) What is the molecularity of the reaction in Step II ?

                          CBSE CLASS XII Previous Year Papers

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