Have you ever tried washing dishes without soap? It doesn’t work well, especially if there’s a lot of grease, fat, or oil on the dish!


The oils and fats are slippery and repel water, which makes them a great choice for lubration of bearing and wheels, but lousy for cleaning up after dinner.


So what’s inside soap that makes it clean off the dish? The soap molecule looks a lot like a snake, with a head and a tail. The long tail loves oil (hydrophobic) and the head loves water (hydrophilic). The hydrophilic end dissolves in water and the hydrophobic end wraps itself around fat and oil in the dirty water, cleaning it off your dishes.


Let’s do an experiment that will really make you appreciate soap and fat:


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Materials:


  • whole milk (if you have it – otherwise, use lowfat)
  • food dye
  • bowl
  • liquid soap


 


Download Student Worksheet & Exercises


While it may not look like it (or taste like it), milk is mostly water with minerals, proteins, and fat trapped inside. When you add a drop of soap, the hydrophobic end races around and grabs the fat and links up with other tail ends of soap molecules, forming the colors you see in the dish. The higher the fat content of your milk, the longer the show.
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Comments

24 Responses to “Cool Milk Trick”

  1. Sure! Try it with cooking oil and water instead of milk.

  2. Linda Griffith says:

    can yiu use something other than milk

  3. Absolutely! Whole milk works best.

  4. Brett Barkley says:

    This is so cool,and can you use milk with fat in it?

  5. Let me know if it works… it should!

    Aurora

  6. Andrea Albury says:

    is it okay if we diluted the milk already?

  7. Brook Batzel says:

    #this type of art is better then me!

  8. Brook Batzel says:

    im a pretty good artist im not nearly good as one of my friend’s art neither as good as this type of art!

  9. Brook Batzel says:

    i’ve only done the waterscope
    ill have to do this on saturday LOL!

  10. You try it and see if it works! 🙂

  11. Melanie Church says:

    What if you do it with Almond Milk.

  12. Michelle Stevens says:

    Thanks!

  14. Michelle Stevens says:

    So if I use a lot more whole milk then the show will be longer?

  15. Make sure you’re logged in first!

  16. Priscila Gonzalez says:

    where is the video?

  17. Maria Ordaz says:

    we tried it with almond milk and it worked really well! 🙂 thanks so much-Japhet age 11

  18. Roderic Sisk says:

    Wow. We must have spent 20 minutes staring into that bowl. You can continue to add new drops of soap after the last calms down. It’s like watching nebulae form. The boys loved it.

  20. Angelyn Tag says:

    wow looks super cool

  21. Angelyn Tag says:

    Wow!!!!Looks SO cool can not wait to try it oh..question!! Will dish soap work okay for this,or do you have to use hand soap? Does it make any difference? Maria, age 10

  22. Carolyn Halvorsen says:

    Looks really cool right now

  23. Lisa West says:

    Very cool. Afterwards, the kids decided to see what would happen with canola oil, soap, water, and food coloring. It was cool to watch the different layers of color that they could create. Made for a great learning afternoon. 🙂

  24. Sharon Van Buren says:

    It look like artwork. Cool!