Milk of Magnesia Experiment – Color Changing Liquid Teaches Science Behind Antacids

If you’ve ever wondered how those antacids really work inside your stomach, the Milk of Magnesia demo is easy to perform and really illustrates the concept of pH change and the buffering power of magnesium hydroxide. I first saw the demonstration performed by Sue Ann Berger during a Flinn Morning of Chemistry many years ago. She originally called the demonstration M.O.M. to the Rescue, and the audience reaction from her standing room only crowd was fantastic. The Milk of Magnesia demo is a favorite among chemistry teachers because of the visual way it teaches the buffering action of magnesium hydroxide. I recently shared this cool science demo on 9News.

Read the Color Changing Milk of Magnesia Experiment

Watch the Milk of Magnesia Experiment Video

Milk of magnesia is a liquid used as an antacid and, sometimes, a laxative. Also known as magnesium hydroxide or Mg(OH)2, the solution is taken orally. The original concentrated formula was concocted by a man named Charles Henry Phillips in 1880, and sold under the brand Phillips’ Milk of Magnesia. Today, the rights to the name “milk of magnesia” appear to be owned by Bayer Corporation and, interestingly, “Phillips’ Milk of Magnesia” is owned by Sterling Drug.

Milk of magnesia is an alkaline suspension, meaning that it undergoes a neutralizing reaction when encountering anything acidic. This makes it an effective combatant of excess stomach acid when taken internally. Too much hydrochloric acid (HCl) excreted by the parietal cells in the stomach can lead to indigestion, heartburn and stomach ulcers. Milk of magnesia in the form of an antacid is dosed from 500 mg-1.5 mg (0.02-0.05 oz) and readily enters the stomach, where the hydroxide ions in milk of magnesia combine with the hydrogen ions in HCl to calm overactivity in the stomach.

20 replies
  1. dianna
    dianna says:

    this is great! i need a really good sience project for my age.i am in 5th grade i need help send me some ideas also lvoe your ideas but they are to imature.

    thanks dianna

    • Fiona
      Fiona says:

      Hello! my name is Fiona I am in 6th grade I wanted to give u some information for u’r project:

      Milk is mostly water, but, it contains vitamins, minerals,proteins and tiny droplets of fat.

      Hope it’ll work!

      see ya!

  2. Gerald
    Gerald says:

    This I think is a wonderful science project for children, but has anyone thought to mention that the use and over use antacids can cause great harm. In a study of 500,000 patients written and published in The Journal of the American Medical Association, scientists concluded that antacids in fact make your digestive system much more welcoming for malicious harmful bacteria and viruses-and that can open the flood gates to all sorts of complications. They discovered that individuals taking acid-suppressing medications were 4.5 times more likely to get pneumonia than those who hadn’t taken the drugs!

  3. sarah
    sarah says:

    how does this work? i need to know for my science experiment. i know it says on the site but its too scientific..any help please? 🙂

  4. RubixCube5000
    RubixCube5000 says:

    So what exactly does this represt? Just the color changes, or could I add food and show how it digests/dissolves? Please help soon it’s for an important project.

  5. Joel
    Joel says:

    This helps me a lot. I took it twice in a row to make sure all that is bothering inside my stomach is gone. As a matter of fact Im inside the toilet now at 4:42 in the morning.


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