Does the salt water requires more energy to be freezed with a fridge compared to distilled water?
If so, why and how much more?
thats a two pronged problem. It takes less energy to cool saltwater from 10 degrees C to 0 degrees C (because Heat Capacity is less) but saltwater freezes at lower temperature (-1.91 degrees C). So while its a little easier to cool, you have to cool it almost 2 degrees further to freeze it. The amount of heat to freeze is known at latent heat of fusion. I can't find a difference for the latent heat value so I'll assume they are equal. Hence after reaching freezing point, it takes same loss of energy to freeze (change phase) of salt water and fresh water. Without knowing the mass of the water I'd guess it takes a little less effort to cool and freeze saltwater. If you need a more complete answer give the mass of the water. I assumed they the same mass for fresh water and saltwater. Answer also depends on the salinity (how salty) of the salt water. The differences are maximized at a certain level of 'saltiness'.