Question

You have a crate of 40,0 kg of shrimp at 8,0°C. You want to freeze the shrimp to a temperature of -18,0°C. How much warmth must be removed from the shrimp to make this happen? The following is given: The freezingpoint for the shrimp is -2,2°C. The melting ethalpy for the shrimp is 277 kJ/kg. The spesific heat capacity for the shrimp before they freeze is 3,62 kJ/kg.°C. The shrimps specific heat capacity after the freezing point is 1,89 kJ/kg.°C.

Answer 1

The Mass of shrimp is 40 kg

Initial temperature is 8.0^o C

Final temperature is -18.0^o C

Since freezing point is -2.2^o C, from  8.0^o C to -2.2^o C sensible heat is required and then latent heat for phase change.

So, heat required  8.0^o C to -2.2^o C =mxCx(T₂-T₁)

=40 kg x 3.62 kJ/kg C x (8-(-2.2))

=1476.96 kJ

Latent heat for phase change=m x 277 kJ/kg

=40 kg x 277 kJ/kg

= 11080 kJ

Sensible heat from -2.2^o C to -18.0^o C =mxCx(T₂-T₁)

=40 kg x 1.89 kJ/kg C x (-2.2-(-18))

=1194.48 kJ

So, total heat is sum of the heats equal to 1476.96 kJ +1194.48 kJ+11080 kJ

=13751.4 kJ