Chapter 15 Classification of Matter Composition of Matter

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Chapter 15 Classification of Matter

Chapter 15 Classification of Matter

Composition of Matter

Composition of Matter

Pure Substances n Elements n Smallest amount – atom, can have molecules n Periodic

Pure Substances n Elements n Smallest amount – atom, can have molecules n Periodic table n Compounds n Smallest amount – molecule n Two or more elements chemically combined

Mixtures n Homogeneous – “same” “Evenly” or “well” mixed n Solutions – Solute dissolved

Mixtures n Homogeneous – “same” “Evenly” or “well” mixed n Solutions – Solute dissolved in Solvent n Light will pass thru (transparent) n Ex. : kool-aid, saltwater, soft drinks, antifreeze n Colloids – Solute permanently suspended n Cloudy – light is scattered n Ex. : milk, toothpaste, smoke, whipped

Types of Solutions n n n n gas in gas : air ( N

Types of Solutions n n n n gas in gas : air ( N 2, O 2 , Ar, CO 2 , other gases) gas in liquid : soft drinks (CO 2 in water) liquid in liquid : gasoline (a mixture of hydrocarbon compounds) solid in liquid : sea water ( Na. Cl & other salts in water) gas in solid : H 2 in platinum or palladium liquid in solid : dental amalgams ( mercury in silver) solid in solid : alloys ( brass, (Cu/Zn), solder (Sn/Pb)

Examples of Colloids n n n n gas in liquid : whipped cream gas

Examples of Colloids n n n n gas in liquid : whipped cream gas in solid : foam liquid in gas : fog liquid in liquid : mayonnaise liquid in solid : fruit pulp solid in gas : smoke solid in liquid : gelatin solid : ruby glass (colloid of gold in glass)

Examples of mixtures

Examples of mixtures

Mixtures n Heterogeneous – “different” “Least” or “not evenly” mixed n. Not the same

Mixtures n Heterogeneous – “different” “Least” or “not evenly” mixed n. Not the same throughout Ex. – concrete, beef stew, taco’s Clothing, oil and vinegar dressing

Mixtures n Heterogeneous – “different” “least” or “not well” mixed n Suspensions – particles

Mixtures n Heterogeneous – “different” “least” or “not well” mixed n Suspensions – particles are larger than colloids n Suspensions are "murky" or "opaque". They do not transmit light. Suspensions separate on standing. The mixture of particles can be separated by filtration. n Ex. Blood, aerosol spray, medications (shake well before using)

Mixtures can be separated n By weight - In many cases, the difference in

Mixtures can be separated n By weight - In many cases, the difference in weight of the substances will allow the effect of gravity to separate them. A centrifuge will accelerate the effect of gravity by using centrifugal force to separate the materials. It is possible to separate the milk and cream particles (or cream globules) by spinning the liquid in a centrifuge. Hospitals use the centrifuge to separate blood cells from the plasma, which can be preserved longer. n Evaporation/Boiling - Changing a liquid into a gas can often separate liquid mixtures. This can be done by natural evaporation or by boiling the liquid mixture. This is often done in separating salt-water solutions.

More ways to separate mixtures n Sifting/Filtering n Sifting materials of different sizes can

More ways to separate mixtures n Sifting/Filtering n Sifting materials of different sizes can separate some mixtures. (Coffee/Tea) n Magnetism n If you had a mixture of iron filings and some non-magnetic material, you could use a magnet to separate

17. 2 Properties of Matter n Physical Properties : color, odor, taste, size, shape,

17. 2 Properties of Matter n Physical Properties : color, odor, taste, size, shape, texture, luster, hardness, density, mass, volume, weight, melting pt. , boiling pt. , malleability, ductile n Physical Change : a change in any one or more of the above properties. A physical change does not change identity of the substance.

17. 2 Properties of Matter Chemical Properties : flammability, reactivity, p. H, combustibility, ability

17. 2 Properties of Matter Chemical Properties : flammability, reactivity, p. H, combustibility, ability to rust, fermentation. n Chemical properties are only observ-able during a chemical reaction. n

17. 2 Properties of Matter n Chemical changes, or chemical reactions, are changes that

17. 2 Properties of Matter n Chemical changes, or chemical reactions, are changes that result in the n n n production of another substance. When you burn a log in a fireplace, you are carrying out a chemical reaction that releases carbon. When you light your Bunsen burner in lab, you are carrying out a chemical reaction that produces water and carbon dioxide. Common examples of chemical changes that you may be somewhat familiar with are; digestion, respiration, photosynthesis, burning,

17. 2 Properties of Matter n Law of Conservation of Mass : n Matter

17. 2 Properties of Matter n Law of Conservation of Mass : n Matter cannot be created or destroyed, it can only change forms. n mass of reactants = mass of products n Matter is always conserved in chemical reactions, the matter may be in a different form, but it never disappears.