H 2 O(s) H 2 O(l) Is it still the same substance? Have the physical properties changed?

2C 20 H 42 (s) + 61O 2 (g) 42H 2 O(g) + 40CO 2 (g) In the presence of a flame: Is it still the same substance? Have the physical properties changed?

2C 20 H 42 (s) + 61O 2 (g) 42H 2 O(g) + 40CO 2 (g) If the flame cools down: Does the candle come back? ?

2C 20 H 42 (s) + 61O 2 (g) 42H 2 O(g) + 40CO 2 (g) If the flame cools down: The candle does not come back by itself. X In this chemical reaction, the atoms were rearranged. This change is irreversible. Therefore the substance has undergone a chemical change

What is a physical property? A characteristic that can be observed or measured without changing the sample’s composition

What is a Chemical Property  The ability of a substance to combine with or change into one or more other substances

What Defines a Physical Property  Change that alters a substance without changing its composition  Examples- I can cut a log in half. Have I actually changed the wood?

What Defines a Chemical Property  Process that involves one or more substances changing into new substances

Indications that a CHEMICAL change has Occurred  Formation of a gas  Formation of a solid  Color change  Temperature/energy change  Odor/smell

Extensive vs Intensive Properties  Extensive  Dependent upon the amount of substance present  Ex. Mass, length, volume  Intensive  Independent of the amount of substance present  Ex. Density, hardness, temperature **Chemical Properties are ALWAYS intensive**

Qualitative vs Quantitative  Quantitative data is information about quantities; that is, information that can be measured and written down with numbers. Some examples of quantitative data are your height, your shoe size, and the length of your fingernails  Qualitative data is information about qualities; information that can't actually be measured. Some examples of qualitative data are the softness of your skin, the grace with which you run, and the color of your eyes.

Scenarios  The age of your car.  The number of hairs on your knuckle.  The softness of a cat.  The color of the sky.  The number of pennies in your pocket.