Chapter 2: Properties of Matter Section 1 Chapter 2 Opening Demonstration How are these two cans alike and different? If we put these two drinks in water would they float or sink??? Lets Try! Who is Right?? This will work for any regular and diet drink! Objectives Describe physical & chemical properties. Give examples of physical changes. Explain that chemical changes form new substances. Observe signs of chemical changes in an experiment. Physical Properties We use physical properties to describe an object or a person! How would you describe these objects? Matter has observable properties Physical Properties the characteristics of a substance that can be observed without changing the identity of the substance. Your senses can be used to detect physical properties. Examples: Color, shape, size, texture, volume, mass. How do you know which characteristics are physical properties? Just ask yourself whether observing the property involves changing the substance to a different substance. Density Mass & Volume are two physical properties Density is a measure of the amount of matter present in a given volume of a substance. Density= MassD= m Volume V Can you Determine??? How would you find the density of 200 g of clay with a volume of 100 cm 3. Density is a property of a substance that remains the same no matter how much of a substance you have! Density A glass marble has a volume of 5 cm 3 and a mass of 13 g. What is the density of glass? Answer: D= 2.6 g/cm 3 Physical Changes A change in any physical property of a substance, not in the substance itself.\ Examples: Stretching a Rubber Band Ice melting Chemical Properties Up your nose. Why is Lady Libertys nose so shiny? It needs to be powdered? NO! When Tori and Alex rub her nose, the oils on their skin remove the tarnish (a chemical reaction); revealing the untarnished alloy. Olis from their hands also protect the alloy from reacting with the air and forming more tarnish. Do you think they pulled out an alloy booger? Chemical Properties Chemical Properties describe how substances can form new substances. Examples: Combustibility Iron Rusting Silver Tarnishing Cooking (boiling Eggs) The only true indication of a chemical change is that a new substance has been formed. Signs of a Chemical Change You may or may not be able to observe many chemical changes. If you observe 2 or more of these signs during a change, you are most likely observing a chemical change. Production of an Odor Change in Temperature Change in Color Formation of Bubbles Formation of a Solid Formation of an Odor Some chemical changes produce smells. The chemical change that occurs when an egg is rotting produces the smell of sulfur. Thunderstorms also produce an odor. The odor is an indication that lightning has caused a chemical change in the air. Lightning storm over Iraq~ Oct 07 Lightning over Camp Adder in Iraq God must hate this place as much as we do Captain Jason deFoor Change in Temperature Chemical changes often are accompanied by a change in temperature. Example: Logs burning in a campfire Change in Color A change in color is often an indicator of a chemical change. Example: Fruit may change color when it ripens. Formation of Bubbles The formation of gas bubbles is another indicator that a chemical change may have occurred. Example: Antacid tablet in water Formation of a Solid When two liquids combine, a solid called a precipitate can form. Examples: Shells of animals such as clams and mussels are precipitates. They are the result of a chemical change involving substances combining with substances from the creatures. Review What is a Physical Change? Give an example. What is a Chemical Change? Give an example. What is density? What is the formula? What are the signs of a Chemical Change?
