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GRADE 7 SCIENCE (MIXTURE).pptx
- 1. SUBSTANCES AND MIXTURES GRADE 7SCIENCE WELCOME TO MY CLASS!
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- 7. HETEROGENOUS AND HOMOGENOUS MIXTURES! •Rocksandairareexamplesofthetwodifferenttypesof mixtures •heterogeneousandhomogeneous. •It’snotalwayseasytoidentifyamixture.Arocklookslike amixture,but airdoesnot.
- 8. HETEROGENOUS MIXTURES •A heterogeneousmixtureisamixture inwhichsubstancesarenotevenly mixed. •Often,youcanseethedifferent substancesandpartsofa heterogeneous mixturewithunaided eyes.Sometimesyoucanseethem onlywitha microscope.
- 9. •Bloodlooksevenlymixed—its colorandtexturearethesame throughout. •Supposeyoucomparetwo samplesofbloodundera microscope.They will look different.Thesampleswill contain differentamountsof the components (plasma,rbc, wbc,platelets)
- 10. HOMOGENOUS MIXTURE •Ahomogeneousmixtureisamixtureinwhich twoormoresubstances areevenlymixedonthe atomiclevelbutnotbondedtogether . •Theindividualatomsorcompoundsofeach substancearemixed. •Airis ahomogeneousmixture. •Anothernameforahomogeneousmixtureis solution. C6H12O6 H20 H20 C6H12O C6H12O6 H20
- 11. EXAMPLE OF HETEROGENOUS: ICECUBE ASSORTED NUTS MIXTURE OF WATER AND OIL
- 12. EXAMPLE OF HOMOGENOUS MILKSHAKESUGAR STEEL
- 13. TYPES OF MIXTURES! Thereare three families of mixtures: solutions, suspensions and colloids. Solutions are homogeneous while suspensions and colloids are heterogeneous.
- 14. SOLUTION! • Solutions arehomogeneous mixtures that contain a solute dissolved in a solvent, e.g. salt dissolved in water. When the solvent is water, it is called an aqueous solution. The ratio of mass of the solute to the solvent is called the concentration of the solution. • Solutions can be liquid, gaseous or even solid. Not only that, the individual components of the solution can be different states of matter. The solute assumes the phase (solid, liquid or gaseous) of the solvent when the solvent is the larger fraction of the mixture.
- 15. GASEOUS SOLUTION! • Whenthe solvent is a gas, it is only possible to dissolve gaseous solutes in it. The most common example of a gaseous solution is the air in our atmosphere, which is nitrogen (the solvent) and has solutes like oxygen and other gases.
- 16. LIQUID SOLUTIONS! • Liquidsolvents are capable of dissolving any type of solutes. • Gas in liquid: Examples include oxygen in water, or carbon dioxide in water. • Liquid in liquid: Example include alcoholic beverages; they are solutions of ethanol in water. • Solid in liquid: Sugar or salt solutions in water are examples of such mixtures. Many solid in liquid mixtures are not homogeneous so they aren't solutions. They could be colloids or suspensions.
- 17. SOLID SOLUTIONS! • Solidsolvents can also dissolve solutes of any state of matter. • Gas in solid: An example of this is hydrogen dissolved in palladium • Liquid in solid: Examples of this include mercury in gold, forming an amalgam, and water (moisture) in salt • Solid in solid: Alloys like steel, brass or bronze are an example of such mixtures.
- 18. SUSPENSIONS! • A suspensionis a heterogeneous mixture that contains solid particles that are large enough for sedimentation. The solid particles do not dissolve in the solvent but are suspended and freely floating. They are bigger than 1 micrometer and are usually large enough to be visible to the naked eye. An example is sand in water. A key feature of suspensions is that the suspended particles settle over time if left undisturbed.
- 19. COLLOIDS! • Colloids areheterogeneous like suspensions but visually appear to be homogeneous because the particles in the mixture are very small—1 nanometer to 1 micrometer. The difference between colloids and suspensions is that the particles in colloids are smaller and that the particles will not settle over time.
- 20. HOW DO COMPUNDSAND MIXTURE DIFFER? •Thesubstancesthatmakeupamixturearenotchemically bonded. •Mixing is aphysicalchange.Thesubstancesthatexist beforemixingstill existinthemixture.
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- 22. COMPOUNDSDONOTKEEPTHEIRPROPERTIES •Theproperties of acompound can bedifferent from the properties of the elementsthatmakeitup. •Sodium and chlorine bond and form table salt. Sodium is a soft, opaque, silvery metal. Chlorine is a greenish, poisonous gas. Y ou cannotobserve anyoftheseproperties intablesalt.
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- 25. THANK YOU SOMUCH AND HAVE A GREAT DAY EVERYONE!