Sciene Oil In Water

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Oil-in-Water & Water-in-Oil Emulsions Introduction In this activity we will compare water in oil emulsions and oil in water emulsions with water-soluble food coloring. Material 5 small cups Microscope slides Food coloring 5 coffee stirrers Whole milk Butter Margarine Mayonnaise Vinaigrette dressing To Do and Notice Bring butter and margarine to room temperature before the start of the activity or melt 1 tablespoon of each in the microwave for 30 seconds. Measure out approximately one tablespoon of butter, whole milk, margarine, mayonnaise, and salad dressing into 5 separate small cups. With a dropper place a few drops of food coloring onto the surface of each sample. Mix each sample with a coffee stirrer then use the stirrer to spread a thin layer of each stained sample on a microscope slide. Observe each sample to see if the surrounding matrix is stained, or tiny bubbles within the matrix. You may need a magnifying glass to see more detail in each emulsion. Can you determine which foods are water in oil emulsions? Which foods are oil in water emulsions? What’s going on? An emulsion is a stable mixture of two substances that do not normally mix such as oil and water. Mayonnaise, homogenized whole milk (a mixture of butter fat or cream and milk), butter, margarine, and vinaigrette salad dressing are common emulsions. We can determine which of these emulsions is a mixture of tiny droplets of oil in water, or tiny droplets of water in oil using fat-soluble and water-soluble dyes. Food coloring  is a water-soluble dye and so will stain the components in a sample that are made up of mostly water. Food coloring does not easily stain fats. You should observe either tiny clear bubbles within a colored matrix, or tiny colored bubbles within an unstained matrix. A vinaigrette salad dressing is the oil in water (or vinegar) variety, along with milk and mayonnaise.

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