Mixtures and Solutions Science Resources - FOSS® Next Generation™

Y ou made a mixture of gravel and water in class. You put 50 milliliters (mL) of water and a spoonful of gravel in a cup, and the job was done. Then you separated the mixture of gravel and water. You poured the mixture through a screen. The gravel stayed on the screen, and the water passed through. All mixtures can be separated. But not all mixtures can be separated in the same way. The physical properties of the materials in the mixture can be used to separate the mixture. Particle size is a physical property of gravel. Particle size is a physical property of water. The particles of gravel are larger than the holes in the screen. The particles of water are smaller than the holes in the screen. The screen can be used to separate the mixture. In class, the mixture of diatomaceous earth and water passed through the screen. The particles of the powder and water are both smaller than the holes in the screen. What property will separate powder from water? The answer is size again. Powder particles are larger than the holes in filter paper. Water particles are smaller. Filter paper will separate a mixture of powder and water. Other Ways to Separate Mixtures Imagine you open a drawer to get a rubber band. Oops, the rubber bands spill. So do a box of toothpicks and some nails. The drawer has an accidental mixture of nails, toothpicks, and rubber bands. How can you separate the mixture? Taking Mixtures Apart A screen can separate gravel and water. 8

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