Ice may appear lighter than water because it floats. This is not a function of weight but of density. Ice weighs the same as the water it was made from. However, it is less dense and takes up about 10% more space. Any object in water displaces only its own weight in water. For that reason, ice floats.
So if your "gallon" of ice is a frozen gallon of water, it will weigh 8.33 pounds.
If the "gallon" (volume measure) is the actual ice itself, it is going to weigh (and be made from) about 10% less than a gallon of water. About 7.497 pounds.
Answered by Yash
at
10:09 PM on December 05, 2008