Chemistry Chemical/Physical Properties & Changes

What is Matter? Think and Discuss Matter: anything that has mass and takes up space Mass – the amount of matter in something Volume – the amount of space something occupies

What is Matter? Matter is any substance that has both mass and volume. Almost everything around us is matter including air and other gases.

What is a property? Property: a characteristic of a substance that can be observed

Types of Properties 1.Chemical Properties 2.Physical Properties  Quantitative vs. Qualitative Properties

Properties Chemical Property – Describes the ability of a substance to form one or more different substances (ability to participate in chemical reactions) –The substance is combustible (will burn) –The substance is flammable or reactive Physical Property-The characteristics of a substance that does not involve a chemical change. –Height, weight, colour, etc. –Includes qualitative and quantitative properties

Types of Properties Qualitative properties are descriptive properties. –Example- The car is red. Quantatitive properties involve measurements

Physical Properties continued….. luster malleability: the ability to be hammered into a thin sheet ductility: the ability to be stretched into a wire melting point boiling point density solubility specific heat

Definition of Change Change: the act of altering a substance

Physical change : a change that occurs that does not change the identity of the substance –Melting ice( change in state or phase) –Freezing Kool-aid –Tearing paper –Boiling water

Chemical change: a change that occurs causing the identity of the substance to change –Burning –Digesting food –Reacting with other substances A chemical change is called a chemical reaction

Chemical Change Clues 1.A color change occurs. 2. An odor is produced 3. Formation of bubbles 4.Heat is absorbed or given off. 5.Formation of a precipitate (solid) Keep in mind these are only clues that a chemical change may have taken place. Proof still depends on a new substance being formed with new properties.

Is it a Physical or Chemical Change? The following video will help explain the differences between Physical and Chemical Changes.

#1) Crumpling Paper Notice the creases and folds Is it still paper? Is this a physical or chemical change? Crumpling paper does NOT change the nature of the paper. It puts creases and folds in the paper, but does not alter the paper’s nature. It’s still paper. The shape has changed and there are now creases and wrinkles, but it’s still paper.

#2) Cutting Paper The paper is cut into two pieces. Is it still paper? Was this a physical or chemical change?

#3 Adding salt to water BACKGROUND Water boils at 2120F It changes from a liquid into a gas (water vapor). This is called evaporation. When it cools, it condenses back into a liquid. This is called condensation. When water evaporates only the H2O molecule changes state. All other substances stay behind. Evaporating and then condensing water in order to purify the water is called distillation.

#4) Melting & Hardening Wax At room temperature wax is a solid. When you light a candle, the wax melts and can be poured like a liquid. When the wax cools, it hardens into a solid. Is it still wax?

#5) Burning Paper In order for combustion to occur you need a fuel, sufficient heat, and oxygen Combustion is evidence that a chemical reaction is taking place. Heat is given off (it’s exothermic). Light is given off; and, the substance (in this case, paper) is no longer the same. When paper is burned carbon dioxide and water are also produced in the chemical reaction

#6 Burning Steel Wool ayer_embeddedhttps:// ayer_embedded

#7) Glow Sticks

Summary What are some evidences of physical changes? What are some clues to chemical changes?

States of Matter Solid, liquid, and gas