Ice, Water, salt and Ice cream

I have mentioned this very briefly in one of my earlier posts, entitled Measurements and Density. This time, I shall post more about it. Firstly, the density of ice is less than that of water. This is obvious as ice cubes float in a glass of water when you put them in. Simple right? But why is this so? Well, the answer is simple: When water freezes to form ice, it traps air in it. Air is less dense than water, so it causes the ice to float.

Secondly, if a glass is filled with water and ice cubes are placed in the glass, when the ice cubes melt will the water level rise? The answer is no, the water level will NOT rise. At first, I also thought that the water level would rise. However, once I read the explanation, it made perfect sense. The reason is that when ice melts, its volume is still the same so it will take up the same amount of space that it took up when it had not melted yet.

Lastly, we were asked to research on the effects of impurities on water. Well, this is what I know: In cold countries, salt, an impurity, is thrown on the roads to melt the snow and ice. This is because impurities lower the melting point of ice. This same concept is applied to make ice cream. You can just pour sugar and milk into a freezer bag and seal it, then place it into a larger bag, already filled with crushed salt. Make sure both bags are tightly sealed, and then shake the bags vigorously(but not so vigorously that they split open or smash!) After some time, the contents should solidify and turn into delicious homemade ice cream!

I found a video on Youtube summarising the above instructions in a 1min 18 sec clip. Enjoy!

http://www.elmhurst.edu/~chm/vchembook/122densityice.html

http://sg.answers.yahoo.com/question/index;_ylt=AqAdCXkAnMkY8xceJjXqoAQh4wt.;_ylv=3?qid=20080208133726AAWySCd

http://www.wikihow.com/Make-Ice-Cream