What is the value of M?

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An insulated copper beaker of mass M contains 300 grams of water at 760 You add 120 grams of Ice at -200C. The final stable temperature is 33.70C. What is the value of M? (Sp. Heat of copper = 386 J/kg.0C, Sp. Heat of water = 4186 J/kg.0C, Sp. Heat of ice = 2110 J/kg.0C, Latent heat of fusion of ice = 334000 J/kg.)

a) 0.50 kg

b) 0.61 kg

c) 0.65 kg                  

d) none of these.

Expert Solution
Step 1

Principle of Calorimetry

When two bodies of unequal temperatures are kept in thermal contact, heat exchange occurs until the two bodies reach a steady common temperature. The heat lost by the hot body is equal to the heat gained by the cold body.

Heat Lost by hot body = Heat Gained by cold body

If c is the specific heat of a substance then the amount of heat required for T change of m kg os that substance is given by

               Q=mcT

Step 2

The mass of the copper beaker =M

Mass of the water already present in the beaker =300g=0.3 kg

The common temperature of the water and the beaker T1=76°C=76+273 =349 K

Final stable temperature Tf=33.7°C=33.7+273=306.7 K

Specific heat of copper c1=386 J/kg K

Specific heat of the water c2=4186 J/kg K

Heat lost by the copper beaker to reach the steady temperature =Mc1T1-Tf=M×386×349-306.7=16327.8 M

Heat lost by the water to reach a steady temperature =0.3×4186×349-306.7=53120.34 J

Total heat lost 

          Q1=16327.8 M+53120.34

Mass of water in the ice =120 g=0.12 kg

The initial temperature of ice T2=-20°C=-20+273=253 K

Specific heat of ice =2110 J/kg K

Amount of heat gained by ice to reach its melting point =0.12×2110×273-253=5064 J

Latent of fusion of ice L=334000 J/kg

Amount of heat gained to melt the heat completely =ML=0.12×334000=40080 J

Amount of heat required by the water in ice to increase the temperature from the melting point to the steady temperature =0.12×4186×306.7-273=16928.184 J

Total heat gained for the entire process

Q2=5064+40080+16928.184=62072.184

According to the principle of calorimetry

Q1=Q2

This gives

16327.8M+53120.34=62072.18416327.8M=62072.184-53120.34=8951.844M=8951.84416327.8=0.55 kg

 

 

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