Chapter 2: Matter and Its Changes The phosphorous compounds in this match combust in the presence of atmospheric oxygen (O 2 ) Studying the compounds in the match and how they react are a main focus of chemistry.

Chapter 2: Matter and Its Changes Matter is anything in the universe that has mass and volume. Mass is a measure of how much matter an object has. Volume is defined as how much space an object takes up. When matter has a uniform, definite composition it is called a substance. (ex: gold, chlorine, sucrose, sodium chloride)  needs to be “pure”

Chapter 2: Matter and Its Changes We can describe substances in terms of their physical properties: color, odor, melting point, boiling point, density.

Chapter 2: Matter and Its Changes Matter exists in three states: solid, liquid, and gas. What is a vapor then? Vapor is the gas form of a substance that is normally a solid or liquid at room temperature and pressure. Example: Water is normally a liquid at room temperature, therefore gaseous water is usually called water vapor (steam).

Chapter 2: Matter and Its Changes Physical changes occur when the composition of the matter does not change. Examples include: moving from one phase to another (boiling, freezing, melting, condensing,etc.) other physical alterations (bending, cracking, breaking, cutting, crushing, etc.)

Chapter 2: Matter and Its Changes In-class exercises: Answer pg. 31, #2 and #3.

Chapter 2: Matter and Its Changes Section 2: Mixtures A mixture is a blend of two or more substances. Their compositions may vary. Two types of mixtures exist: heterogeneous and homogenous mixtures. - Heterogeneous: composition is not uniform (salad dressing) - Homogeneous: composition is completely uniform (salt water)

Chapter 2: Matter and Its Changes Section 2: Mixtures Homogeneous mixtures are called solutions. Solutions do not have to be a solid in a liquid. Check out pg. 33, Table 2.3 Homogeneous solutions have one phase. Heterogeneous solutions can have two or more phases. Salt water – 1 phase ; Oil and water – 2 phases

Chapter 2: Matter and Its Changes Section 2: Mixtures You have a mixture of sand and iron fillings. How could you separate these two substances? You have a mixture of sand and iron fillings, but this time you accidentally spilled distilled water on them obtaining a sand, iron, water mixture. How do you separate all three? You have a mixture of salt and water. How could you separate the two? Hint: Check out pg. 33 “Separating Mixtures”

1.Use a magnet to pull the iron from the sand. 2.Again, use the magnet to remove the iron. Distill the sand and water solution to separate those two substances. 3.Distill the mixture. (Or boil the water away)