Why do ice cubes appear white even though water is transparent?
The center of an ice cube is white because it is full of bubbles and other defecrts like cracks and boundaries between ice crytsals. They are found in the center more than at the surfaces because the the water freezes from the outside in, and at a fairly slow raTe. This allows the outer ice to solidify with fewer defects than the later ice. This is a major problem in casting metals and other things as well. http://www.newton.dep.anl.gov/askasci/chem99/chem99073.htm Hard water contains minerals like calcium that condense when frozen, which will cloud up ice cubes. As water freezes, dissolved air is forced out as a gas, which forms bubbles. These bubbles are trapped in the ice, making it look opaque.