Details activity Length 30 mins. topics ArtMixtures Activity kind Discrepant occasion (Investigatable) Language English print

In general, fat and water execute not mix; liquids favor these that perform not form a homogeneous (uniform) mixture are called immiscible.

When food colouring is inserted on the surface of milk, the autumn remains intact with little spreading. The water-based food colouring does no mix through milk easily, due to the fact that milk is a suspension of fat molecule in water and food colouring is a water-like dye.

Once the soap is added to the milk, it spreads over the surface and causes the food colouring come move quickly thorough the milk and out to the edges of the plate. Because milk is greatly water, it has actually a surface ar tension prefer water. Liquid soap wrecks the surface tension by break the bonds in between water molecules.

You are watching: What happens when you mix water and milk

After the early stage zing of the food colouring, swirling of color ensue as result of the chemical framework of soap. Soap moleculeshave both nature of non-polarandpolarat opposite ends of theirmolecules.

The fat in milk is non-polar. The non-polarhydrocarbon tail that thesoapdissolves right into the fat. The fat-like end of the soap molecules sign up with with the fat in the milk and as the soap spreads across the surface ar of the milk, an ext and much more fat molecules room pulled through the spreading soap. When the fat molecule congregate, the polar water in the milk is moved away, taking the food colouring v it. The motion of the milk decreases together the soap i do not care “used up", or enclosed to every the molecules for which it has room.



Appreciate how soap enables fats or oil to mix v water based solutions.

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Appreciate the liquids have actually surface tension and that soap affects it.


Per student or Group:Homogenized milk (at room temperature)Aluminum pie plateFood colouringDish detergent/liquid soapCotton swabs or little droppers

Key Questions

What happens right away? What happens after 1 minute?

What come Do

pour room-temperature milk in come the pie plate, fully covering the bottom. Allow it come settle.Add as much as 5 fall of food colouring to the milk (any mix of color is okay). Save the fall close with each other in the center of the plate.Dip the cotton finish of the swab in to the soap. Ar the soapy finish of the swab in the middle of the milk and also hold it there for 2 seconds (or use the dropper to present a autumn of soap into the center of the milk).Watch the reaction closely. Notice what wake up immediately and also what happens end time.Continue come experiment by adding another fall of soap.


What happens if you use a various kind that milk? shot using skim, 1%, 2% and also cream. Guess if each will react the very same as the whole milk and also then test to view if you right!

Other Resources

Science civilization Resources | Tourbillon de lait | French version of this resource