![]() ![]() 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. Production of gas (bubbles/fizzing)ġ0 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. 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.ĩ 3 Indicators of a Chemical Reaction 1. New substances formed in the reaction have different properties from the substances present before the reaction occurred. Chemical Changes Chemical change (chemical reaction): one or more substances change into new substances. This is a physical change because while the appearance is the same, the composition of water remains the same (H 2 O).Ĩ Physical Vs. The change of state of matter: change in temperature/pressure can cause a phase change such as melting ice (solid water) into liquid water. Crumpling aluminum foil, cutting a sheet of paper or breaking glass Ex. Chemical Changes Physical change: changes which alter a substance without changing its composition 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. mass, length, volume Intensive properties: physical property independent of amount of substance present Ex. Intensive Properties Extensive properties: physical property dependent upon amount of substance present Ex. Steam is a vapor because at room temperature water exists as a liquidĦ Extensive Vs. neon, methane, air Vapor: Refers to the gaseous state of a substance that is a solid or a liquid at room temperature Ex. water, blood, mercuryĥ Identify the 4 States of Matter Gas: Particles of gases are very far apart Volume: easily compressed because of particle space Ex. wood, iron, paper, sugarĤ 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. 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.ģ 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. ![]() The ability of iron to form rust when combined with air is a chemical property of ironĢ Mass Vs. 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. ![]() 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. ![]()
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