Liquid Nitrogen Ice Cream! Liquid nitrogen is used to freeze a large batch of ice cream for student consumption 9/23/2018

Purpose To understand the properties of a liquified gas To make an edible dessert in a novel way 9/23/2018

Demonstration The liquid nitrogen adsorbed the heat from the cream mixture As it did so, the liquid nitrogen boiled off taking the heat into the atmosphere 9/23/2018

Concepts 1. Biological Molecules 2. Thermodynamics 3. Cryogens 9/23/2018

1. Biological Molecules Biological Molecules are those commonly found in all living organisms Biological molecules Constitute the organism and nourish the organism Milk contains all the three most important biological classes of molecules: Lipids (which are the same as fats and oils) Proteins Carbohydrates (which include all sugars) Milk contains Lipid: Milkfat Protein: Casein Carbohydrates: Lactose (milk sugar) 9/23/2018

2. Thermodynamics Thermodynamics is the study of heat and energy changes The heat in a substance reflects the speed the molecules of the substance are moving The molecules in cream move faster than those in liquid nitrogen, therefore the liquid nitrogen is colder When the cream and liquid nitrogen are mixed the heat in the cream is transferred to the liquid nitrogen, causing the liquid nitrogen to warm above its boiling point and boil away 9/23/2018

3. Cryogens A cryogen is a substance used to cool other substances Liquid nitrogen is nitrogen gas from the atmosphere in which the molecules of N2 have been pressed together using pressure Liquid nitrogen boils away to gas at – 195.79 Degrees Celsius Way Below Room Temperature which is 25 degrees Celsius! 9/23/2018

Conclusions A mixture containing the major three kinds of biological molecules will transfer the motion of those molecules to a cryogen The heat therefore moves from the mixture into the cryogen The cryogen will boil away as it absorbs the heat while the mixture will simultaneously cool and freeze 9/23/2018

Comments The recipe for this ice cream is 4 quarts heavy cream 4 quarts half-and-half (50% milk and 50% cream) 1 cup sugar 3 tablespoons vanilla extract 1 package of M&M candy The liquid nitrogen is not cheap! It costs approximately $40 to make 10 gallons of ice cream! 9/23/2018