This Week's Experiment - #249 Milk Bubbles
This week's experiment comes from a question that I got from the Bingham
family. It has to do with a popular childhood activity, blowing bubbles in
your milk. To try this, you will need:
a glass of milk that is half full (or half empty, depending on your personal
outlook)
a glass of water that is half full
a soda straw
The start is easy. Put the straw in the glass of milk. If the glass is more
than half full, use the straw to drink the excess. Then blow gently through
the straw, making bubbles in the milk. Continue doing this until you fill
the glass with bubbles, or until your mother tells you to stop playing with
your food and get ready for school. (Oops. Sorry. Childhood flashback.)
It was pretty easy to fill the glass with milk bubbles. Next, try the same
thing with the glass of water. This is not nearly as easy. The bubbles pop
very quickly, making it difficult to fill the glass with bubbles without
blowing so hard that you make a mess.
Why the difference? The milk contains milk proteins. These proteins form a
film in the bubble which makes it stronger. The protein film lets the
bubbles last long enough to fill the glass.
The amount of milk fat can also have a big impact on this. Liquid milk fat
forms films in the bubble more easily than the milk protein, but it forms
weaker bubbles. Low fat milk tends to make stronger bubbles than whole milk.
Temperature also has an impact. With a glass of cold milk, the bubbles were
large and lasted quite a while. As the milk warmed up to room temperature,
the bubbles were smaller and popped quickly. This means that you should blow
your milk bubbles early in the meal, instead of waiting to blow bubbles with
your desert.
From Robert Krampf's Science Education Company
PO Box 60982
Jacksonville, FL 32236-0982
904-388-6381
krampf@aol.com
To start receiving the Experiment of the Week, just
send a blank E-mail to: krampf-subscribe@topica.com
|
