Re: Does an ice cube melt faster in air or in fresh water?

The way you want to run your experiment depends on the information you 
intend to gather.  You should decide if you want to collect your data on a 
mass or volume basis.  An important variable to keep constant is the area 
of the ice cube in contact with the air or water.  Heat transfer is a 
strong function of the area of a substance in contact with the temperature 
difference.  

Now that you are keeping the area the same, do you want your results to be 
based on equal volumes or equal masses of air and water?  It is obviously 
more practical to have equal volumes, because of the large quantity of air 
that would be necessary to have an equivalent weight of water.

You will also want to have air and water of equal temperature.  I suggest 
getting a container of water and letting it set in a room so that it will 
come to the same temperature as the air.

At this point, you only have one main variable left- the heat transfer 
coefficient of the fluid (air or water) which is what I am assuming you 
are trying to compare.  Try the experiment out for yourself.

What you would expect to happen is,  under the same circumstances, the ice 
cube in water will melt faster that the one in air.  This is because the 
molecules in a liquid are much closer together than in a gas.  Therefore, 
liquids transfer heat much more efficiently than gases.  Don't take my 
word for it though- this would be a fun experiment to prove!