The chemical formula of Plaster of Paris is:

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The chemical formula of Plaster of Paris is CaSO4·1/2H2O.

Plaster of Paris is a type of building material made from gypsum, a soft mineral composed of calcium sulfate dehydrate. Plaster of Paris is also known as gypsum plaster or just plain plaster.

  • The heating process causes the water molecules in the gypsum to evaporate.
  • This leaves behind calcium sulfate hemihydrate, which is the main component of Plaster of Paris.
  • The calcium sulfate hemihydrate is then ground into a fine powder and packaged for use.
  • When mixed with water, the Plaster of Paris powder rehydrates, forming a smooth, easily workable paste that hardens into a solid mass.

Plaster of Paris has various uses, including:

  1. Making casts and molds for arts and crafts, such as sculptures and candle holders.
  2. Creating models and prototypes, such as architectural models.
  3. Decorative purposes, such as wall and ceiling finishes, cornice moldings, and decorative elements.
  4. Medical uses, such as creating splints and casts for broken bones.
  5. Fireproofing and soundproofing, as it is often used as an ingredient in fireproofing and soundproofing materials.
  6. Agriculture, as it is used in soil improvement and as a fertilizer.
  7. Dental uses, as it is used in dentistry to make impressions of teeth.

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CBSE CLASS XII Related Questions

  • 1.

    (a) Define 'Denatured Protein' with an example.

    (b) What happens when glucose reacts with HCN ? Write the reaction involved.

    (c) Name the disease caused by the deficiency of Vitamin C.


      • 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.
            An organic compound (X) has the molecular formula \(C_5H_{10}O\). Draw structures for (X) if it:
            (I) does not give Tollen's test but gives a positive iodoform test.
            (II) does not give Tollen's test and iodoform test but undergoes Aldol condensation.
            (III) undergoes Cannizzaro's reaction.


              • 4.

                Explain the Finkelstein reaction.


                  • 5.
                    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 ?


                      • 6.

                        (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]

                          CBSE CLASS XII Previous Year Papers

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