Sinking Ice Cubes?

This is a trick: Before the class comes in, place a quantity of water in one beaker and the same quantity of isopropyl alcohol, if your state allows it, in another beaker. In front of the kids, put some water in a smaller beaker, do same with the rubbing alc. Try to make them think its the same stuff. Now place ice cubes in each beaker. Note, cubes in water will float, but sink in isopropyl. Why? Density of isopropyl is about 800 kg/m3 while water's is 1000 and ice's is 917. So, ice floats in the more dense water, but sinks in the less dense isopropyl. CAUTION : Isopropyl is extremely flammable and poisonous if consumed. Do not have open flame and DO NOT get confused between the water and it and take a sip!


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