2. Chapter 3 Notes II CHEMICAL & PHYSICAL Properties/Changes

3. PHYSICAL PROPERTIES color odor Density and hardness Melting point Boiling point solubility A quality or condition of a substance that can be observed or measured without changing the substance’s composition What are some examples?

4. Extensive vs. Intensive Physical Properties Extensive - dependent on the amount of the substance –size, mass, length, volume. Intensive - independent of the amount of the substance –density, boiling pt, melting pt, hardness, magnetism –Help with identification because they are specific to the substance.

5. STATES OF MATTER Matter’s state is a physical property Definite shape, definite volume solid No definite shape, definite volume liquid No definite shape, no definite volume gas

6. States of Matter SOLID Matter that has its own definite shape and volume. Tightly packed solids are incompressible. Due to definite shape, some solids may not take the shape of their container. Not defined by hardness-wax, cheese, etc are solids although not hard.

7. States of Matter LIQUID Matter that flows, has constant volume, and takes up the shape of its container. Particles are not rigidly held in place. Particles packed less closely than in solid. Particles able to move past one another. Regardless of the container, volume stays the same.

8. States of Matter GAS Matter that flows to conform to the shape of and fill its container. Can be compressed due to space in between particles. Particles less close together than solid or liquid. Vapor is NOT the same as a gas. A vapor is the gaseous state of a substance that is solid or liquid at room temp.

9. Change of Phases

10. Kinetic Molecular Theory “All matter consists of extremely tiny particles which are in constant motion.”

11. Chemical Properties Chemical property - A characteristic of a substance that changes when in contact with another substance –Examples????? Flammability Ability to react Rusting of nails Burning of paper

12. PHYSICAL CHANGES Physical Change: –Change in the appearance only, not in its chemical make-up. –Examples: (change in…) Color Shape Temperature Size Phase

13. Chemical Change Chemical changes…changes result in a re- arrangement or recombination of atoms (NEW substance!).Chemical changes…changes result in a re- arrangement or recombination of atoms (NEW substance!). –can’t get original substance back w/out chemical reaction. –Examples: Silver tarnishingSilver tarnishing Apple rottingApple rotting

14. CHEMICAL REACTIONS The ability of a substance to react and form new substances is called a chemical property. In a chemical reaction, one or more substances change into new substances. A reaction starts with the reactants, and the substances formed are called products.

15. How do you know if a chemical reaction is occuring? 4 CLUES TO CHEMICAL REACTION

16. 1) A color change occurs.

17. 4 CLUES TO CHEMICAL REACTION 2) A gas is formed.

18. 4 CLUES TO CHEMICAL REACTION 3) Heat or light is either produced or absorbed.

19. 4 CLUES TO CHEMICAL REACTION 4) A solid is formed from two liquids. This solid is usually called a precipitate.

20. CHEMICAL OR PHYSICAL CHANGE? Baking cookies Boiling water Dissolving salt Burning firewood Milk spoiling Metal rusting Tearing paper Melting ice

21. Law of Conservation of Mass ‘matter cannot be created or destroyed’ ‘matter cannot be created or destroyed’ total mass on reactant side MUST = mass on product side. total mass on reactant side MUST = mass on product side. ~ ‘what goes into the rxn. must come out!’ Ex… Ex… A + B C + D A + B C + D 5 grams 8 grams 2 grams _________ 13 grams 11 grams

22. Density Density…amount of matter present in a given volume. Density…amount of matter present in a given volume. ~ how heavy a substance is D = m/v D = m/v units = g/ml or g/cm 3 units = g/ml or g/cm 3

23. Density problems… Density problems… 1. A nail has a vol. of 0.880 cm 3 and a mass of 6.920 grams. What is the density of the nail? D = m/v D = m/v D = 6.920 g / 0.880 cm 3 D = 6.920 g / 0.880 cm 3 D = 7.86 g/cm 3 D = 7.86 g/cm 3 2. Vegetable oil has a density of 0.916 g/ml. Calculate the mass of 500.0 ml of oil. m = D(v) m = D(v) m = 0.916 g/ml (500.0 ml) m = 0.916 g/ml (500.0 ml) m = 458 grams m = 458 grams 3. The density of a piece of wood is 0.86 g/cm 3. What is the volume of the wood if its mass is 75 grams? v = m/D v = m/D v = 75 g ÷ 0.86 g/cm 3 v = 75 g ÷ 0.86 g/cm 3 v = 87 cm 3 v = 87 cm 3

24. To calculate density of an irregular object… To calculate density of an irregular object… ~ find mass of object using balance ~ find volume of object by using the water displacement method ** water displacement will not work if solid dissolves or floats in water.

25. Separation Techniques It is important to know how to separate mixtures into their component parts. Remember mixtures are physically combined, not chemically combined. Mixtures can be separated using techniques based on their physical properties.

26. Filtration Heterogeneous mixtures composed of solids and liquids can be separated using filtration. Filtration uses a porous barrier to separate solids from liquids. Below filter paper is folded into a cone shape and placed in a funnel, then a mixture is poured through the filter paper. The liquids pour through to filter paper but the solid are trapped by the filter paper.

27. Distillation Most mixtures of homogeneous liquids are separated by distillation. Distillation is based on different boiling points of the substances involved. Distillation is the process of heating a mixture until the substance with the lowest boiling point boils to a vapor, capturing and cooling the resultant hot vapors in a condenser, and collecting the condensed vapors in a receiving flask.

28. Crystallization Homogeneous mixtures can be separated into pure crystals and liquid using crystallization. In order for crystallization to occur, there must be as much of the dissolved solid that the solution can hold. Heating and cooling the solution or adding a small amount of the substance causes the substance to come out of solution and crystals to form. Crystallization is a technique that improves the purity of the solid.

29. Chromatography Components of a mixture can be separated based on the how quickly it moves up the filter paper or stationary phase. In paper chromatography, a sample of the substance to be separated is placed on filter paper. Then it is solvent so that the solvent gradually moves up the paper and separated the mixture into it’s components. Chromatography is used in analytical chemistry to investigate what unknown chemicals are composed of.