1. Classifying Matter

2. Notes on Mixtures There are two basic types of mixtures:
Heterogeneous – different throughout
Example: Orange juice with pulp
Homogeneous – the same throughout
Example: Sugar dissolved in water

3. Solid Mixtures
Alloys – solid solutions that contain different metals and sometimes nonmetallic substances
Example: Steel is a homogeneous mixture of iron and substances such as carbon, chromium, manganese, nickel, and molybdenum

4. Solutions Solutions are homogeneous mixtures
Aqueous solution – A solution where water is the solvent.
Remember that a solute is dissolved, and a solvent does the dissolving.

5. Additional Notes on States of Matter
Volatile – substances that change to gas easily at room temperature.
Chemical properties – can only be observed when there is a change in the composition of the substance.
Chemical change (often referred to as a chemical reaction) – the change of one or more substances into other substances.

6. Additional Notes on States of Matter
Energy – the capacity to do work
Law of conservation of mass – in a chemical change matter is neither created nor destroyed:

7. Review: Exothermic vs. Endothermic
Exothermic – heat exits the system
Endothermic – heat enters the system

8. Homework
P. 44 – Section Review #1,2,3, & 5

9. Density
To determine the density of an object we use the following equation:
D = M/V
Where “D” is the density, “M” is the mass, and “V” is the volume.

10. Units of Density Unit used for mass: Unit used for volume:
Unit used for density:

11. Practice Problems
An object whose mass is 15.0g has a volume of 3.0cm3. What is the object’s density?
An sample of a substance has a mass of 3.0g and a volume of 3.0cm3. What is the objects density? Identify the substance.

12. Density
We can manipulate the density equation to obtain these equations:
M = D*V V = M/D

13. Practice Problems
Setup the following problems using the equations from the previous slide.
Magnesium has a density of 1.74g/cm3. What is the mass of 44.6cm3 of magnesium (Mg)?

14. Practice Problems
Gold has a density of 19.3g/cm3. What is the volume of 33.2g of gold (Au)?
Nitrogen gas has a density of 1.25g/cm3. What is the volume of 12.9g of Nitrogen gas (N2)?

15. Practice Problems
Iron has a density of 9.80g/cm3. What is the mass of 75.9cm3 of iron (Fe)?