TEKS 5.5C The student knows tht matter has measurable physical properties and those properties determine how matter is classified, changed, and used. The student is expected to (C) demonstrate that some mixtures maintain physical properties of their ingredients such as iron filings and sand.
TEKS 5.5D The student knows tht matter has measurable physical properties and those properties determine how matter is classified, changed, and used. The student is expected to (D) Identify changes that can occur in the physical properties of the ingredients of solutions such as dissolving salt in water or adding lemon juice to water.
Color Texture Odor Conducts heat Conducts electricity Magnetic Floats or sinks Solubility Boiling point Melting point Mass What are some physical properties of matter?
Mixtures • Form when two or more substances combine • Keep their physical properties • Can be separated by their physical properties • Do not form a new substance
Salad is an example of a mixture • The lettuce and vegetables do not change when mixed
Is cereal a mixture? Yes…the properties of the substances do not change. You can still see the bananas, cereal, and milk.
Is cake a mixture? No…the properties of the substances change. The eggs, flour, and sugar change when the cake is mixed and baked.
Substances in a mixture can be separated by their physical properties… • Milk and cereal can be separated by pouring the mixture through a strainer.
The cereal would be trapped in the strainer and the milk would pass through.
QUESTION: • How could you separate a mixture of sand and sawdust?
ANSWER: • You can separate the sand from the sawdust by adding water. The sand will sink and the sawdust will float. Sawdust Water Sand
QUESTION: • Which scientific tool could you use to separate a mixture of iron filings and sand?
ANSWER: • You can separate the iron filings from the sand by using a magnet. Iron filings
Solutions are a special kind of mixture • One of the substances dissolves in another • The substance spreads out evenly • Solutions may be clear or colored
You can make a solution when you stir sugar into water. The sugar dissolves and the water remains clear.
Do all substances dissolve? No…if you mix sand with water, the sand does not dissolve but settles on the bottom of the glass. Sand + water
All solutions are mixtures but not all mixtures are solutions • Sugar + Water = ? Mixture and a solution • Sand + Water = ? Mixture but not a solution
Other examples of solutions: • Soda = Gas + Liquid • Jewelry = Solid + Solid • Air = Gas + Gas
Solutions can be separated • Most solutions can be separated by evaporation. • To separate a saltwater solution, let the water evaporate. • Once the water is gone, the salt will be left.
Challenge • You are given a mixture of salt, sand, and gravel. Design a plan to separate this mixture? What tools would you use? List your steps in order.