Q.

Heat energy of 184 kJ is given to ice of mass 600 g at -12°C. Specific heat of ice is 2222.3 J kg-1o C-1 and latent heat of ice is 336 kJ/kg-1.         [2023]

(A) Final temperature of the system will be 0°C.

(B) Final temperature of the system will be greater than 0°C.

(C) The final system will have a mixture of ice and water in the ratio of 5 : 1.

(D) The final system will have a mixture of ice and water in the ratio of 1 : 5.

(E) The final system will have water only.

Choose the correct answer from the options given below:

1 A and D only  
2 B and D only  
3 A and E only  
4 A and C only  

Ans.

(1)

ΔQ=184×103

m=0.600 kg at -12°C

S=2222.3 J/kg/°C

L=336×103 J/kg

Q1=0.600×2222.3×12=16000.56 J

Remaining heat:

ΔQ1=184000-16000.56=167999.44 J

For melting at 0°C

ΔQ2=0.600×336000=201600 J (needed)

100% ice is not melted

Amount of ice melted

167999.44=m×336000=0.4999 kg

 Mass of water=0.4999 kg

       Mass of ice=0.1001 kg

 Ratio=0.10010.49991:5