A laboratory cooling system is used to freeze biological enzyme samples for long-term storage.
Calculate the energy required by the cooling system to lower the temperature of 0.40 kg0.40\text{ kg}0.40 kg of solid enzyme solution from −10∘C-10^\circ\text{C}−10∘C to −40∘C-40^\circ\text{C}−40∘C.
Assume the specific heat capacity of the solid enzyme solution is 2200 J/(kg ∘C)2200\text{ J/(kg }^\circ\text{C)}2200 J/(kg ∘C).
Energy=………………………… J\text{Energy} = \dots\dots\dots\dots\dots\dots\dots\dots\dots\dots\text{ J}Energy=………………………… J
It takes 8 minutes8\text{ minutes}8 minutes for the cooling system to freeze the sample over this temperature range.
Calculate the thermal power removed from the sample by the cooling system.
Power=………………………… W\text{Power} = \dots\dots\dots\dots\dots\dots\dots\dots\dots\dots\text{ W}Power=………………………… W
Suggest two reasons why the actual electrical power drawn by the cooling system during this process is greater than the power calculated in part (a)(ii).
When the enzyme is prepared for analysis, it first has to be changed back into liquid form. The temperature of the solid enzyme is raised to its melting point, but during the melting process, the temperature remains constant.
Explain two reasons why energy is still required to transition the solid enzyme into a liquid at its melting point.
Calculate the number of 8 mg8\text{ mg}8 mg enzyme doses that can be melted using 11200 J11200\text{ J}11200 J of energy.
Assume the specific latent heat of fusion for the enzyme solution is 280000 J/kg280000\text{ J/kg}280000 J/kg.
Number of doses=…………………………\text{Number of doses} = \dots\dots\dots\dots\dots\dots\dots\dots\dots\dotsNumber of doses=…………………………