<span>Mixing cornstarch and water causes a physical change. When the powder cornstarch is mixed with a small amount of water, the mixture is called </span>Oobleck. It is a non-Newtonian fluid; it has properties of both liquids and solids. You can slowly dip your hand into it like a liquid, but if you squeeze the oobleck or punch it, it will feel solid.
Explanation: When you chill a substance when it is mixed with another substance, ( chilled vinegar mixed with sodium bicarbonate will react slower for instance) it reacts slower do to the molecules slowing down when chilled.