Nanocamp June 27, 2012 Chris Marin What is a liquid? All liquids: have a definite volume conform to the shape of container are not compressible are made up of atoms that aren’t in fixed places What is a solid? All solids: have a definite volume have a definite shape are made up of atoms in fixed places What is ice cream?? It has ice in the name, is it a solid? Not quite! See how it took the shape of the glass? Is it a liquid? Not unless you wait to long! It’s both! Colloids A colloid is one phase mixed into another. Ice cream is both a foam, emulsion, and sol! So what is ice cream? In the above microscope image, A is air bubbles, C is ice crystals, F is fat, and S is a solution of liquid. A big part of controlling ice cream’s texture is controlling how much air and ice are in the colloid. nano-ice cream We will be using liquid nitrogen to rapidly make ice cream Normally, ice cream takes hours to make, but liquid nitrogen is extremely cold (-321 °F, or 77 K) The change in temperature when the liquid nitrogen is poured in should be so rapid that the cream doesn’t have time to change to ice Instead, tiny nanometer sized ice crystals should form, like snow does on a very cold day. This should make our ice cream very very smooth!