As a special treat for my General Chemistry students who had to put up with me 5 days a week plus a weekly lab for a full school year, I made liquid nitrogen ice cream for them on Friday.
I love doing this demo because it tastes so good.
Here is my recipe:
2 cups half and half
2 cups heavy whipping cream
1 cup sugar
a healthy splash of vanilla
The ingredients are mixed in a plastic bowl with a wooden spoon. Liquid nitrogen is added in small amounts until the entire mixture assumes a butter-like consistence. I serve it in 3 oz cups.
It tastes great and is loaded with fat. The creams are not light by any means. I've also made a chocolate version, but that is just too rich.
There is also the visually appealing part of making the ice cream.
Students ask a lot of questions about liquid nitrogen. Like: "where can I buy it?" and "does it hurt if it touches you?"
I like to tell the story of when I was reinstalling a cold trap full of liquid N2 on a schlenk line cold finger. Some liquid N2 boiled over and landed in the palm of my hand, I had the choice of dropping the dewar flask or sucking up the pain and finish tightening the clamp. I chose the later and ended up with a nice spot of frost bite on my palm.