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An electric heater 1000W is used to heat 0.2kg of ice. Initially at -10°C to until all the mass changes to steam at 100°C.
Specific heat capacity of ice = 2.1 x 103 JKg-1K-1
Latent heat of fusion of ice = 3.34 x 105 JKg-1
Specific heat capacity of water = 4.2 x 103JKg-1K-1
Latent heat of vaporization of steam = 2.26 X 106Kg-1
Calculate:

  1. The amount of heat required to raise the temperature of ice from -10°C to ice at 0°C.   
  2. The amount of heat required to convert ice into water at 0°C. 
  3. The amount of heat required to raise the temperature of water at 0°C to water at 100°C.     
  4. The amount of heat required to change water to steam at 100°C.     
  5. The minimum time required in minutes for activity in (i) to (iv) to take place 

1 Answer

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  1. Mice x Cice x θ
    =0.2kg x 2.1 x 103 JKg-1K-1 x 10K
    =4.2 x 103J
    =4200J
  2. MwLf
    =0.2Kg x 3.34 x 105JKg-1
    =6.68 x 104
    =66,800J
  3. MwC10 x θ
    =0.2 x 4.2 x 105JKg-1K-1 100K
    =8.4 x 104J
    =84,000J
  4. MLv
    =0.2Kg x 2.26 x 106JKg-1K-1
    =4.52 x 105
    =452,000J
  5. Total heat=4.2 x 105J +6.68 x 104J + 8.4 x 10J +4.52 x 105J
                  = 6.07x 105J
    t=Total heat 6.07x 105= 607s
          Power           1000w
    In minutes =10 minutes 7seconds
                    =10.117 minutes

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