Physical and Chemical Properties of Matter

Transcription

1 Physical and Chemical Properties of Matter What is matter? Anything that has mass and takes up space Chemical or Physical Property? Physical properties of matter: characteristics that can be observed or measured without changing the sample s composition Ex. Density, color, odor, taste, hardness, melting point, boiling point Chemical properties of matter: the ability of a substance to combine with or change into one or more other substances Ex. The ability of iron to form rust when combined with air is a chemical property of iron

2 Mass Vs. Weight Mass: a measurement that reflects the amount of matter Weight: a measure not only of the amount of matter but also the effect of Earth s gravitational pull on that matter The force is not the same everywhere on Earth and actually becomes less as you move away from the Earth s surface at sea level.

3 Identify the 4 States of Matter Solid: Shape: does not change (definite shape) Volume: cannot be made smaller (definite volume) Particles: very tightly packed When heated: expand, but only slightly Ex. wood, iron, paper, sugar

4 Identify the 4 States of Matter Liquid: Particles: not rigidly held in place Less closely packed than are the particles in a solid Move past each other (flows) Shape: may take shape of the container Volume: constant regardless of shape of container; virtually incompressible Ex. water, blood, mercury

5 Identify the 4 States of Matter Gas: Particles of gases are very far apart Volume: easily compressed because of particle space Ex. neon, methane, air Vapor: Refers to the gaseous state of a substance that is a solid or a liquid at room temperature Ex. Steam is a vapor because at room temperature water exists as a liquid

6 Extensive Vs. Intensive Properties Extensive properties: physical property dependent upon amount of substance present Ex. mass, length, volume Intensive properties: physical property independent of amount of substance present Ex. density at constant temp/pressure is always the same regardless of amount of substance present Both are useful when determining the identity of an object Ex. Gold vs. Pyrite

7 Physical Vs. Chemical Changes Physical change: changes which alter a substance without changing its composition Ex. Crumpling aluminum foil, cutting a sheet of paper or breaking glass Ex. The change of state of matter: change in temperature/pressure can cause a phase change such as melting ice (solid water) into liquid water. This is a physical change because while the appearance is the same, the composition of water remains the same (H 2 O).

8 Physical Vs. Chemical Changes Chemical change (chemical reaction): one or more substances change into new substances. New substances formed in the reaction have different properties from the substances present before the reaction occurred. Ex. Crushing grapes to make wine is a physical change, but the fermentation of the juice, sugars, and other ingredients to wine is a chemical change.

9 3 Indicators of a Chemical Reaction 1. Change in color 2. Precipitate (ppt) 3. Production of gas (bubbles/fizzing)

10 Exothermic Vs Endothermic Reactions Exothermic reactions occur when more energy is released forming new bonds than is required to break bonds in the initial reactants. Releases energy feels warm Endothermic reactions occur when a greater amount of energy is required to break the existing bonds in the reactants than is released when the new bonds form in the product molecules. Takes in energy feels cold

11 Law of Conservation of Mass and Law of Conservation of Energy Law of Conservation of Mass: mass is neither created nor destroyed during a chemical reaction it is conserved Mass reactants = Mass products (Mass in = Mass out ) Ex. Mercury (II) oxide yields Mercury + Oxygen 216g mass of reactant = 200g+16g mass of products Law of Conservation of Energy: energy is neither created nor destroyed it is converted between kinetic and potential energies