1. Chapter 8: Substances, Mixtures, and Solubility
Vocabulary
Substance – matter that has the same fixed composition and properties.
Heterogeneous mixture- type of mixture where substances are not mixed evenly
Homogeneous mixture- Contains two or more substances that are evenly mixed on a molecular level but still are not bonded together
Solution- a homogeneous mixture that contains two or more substances that are evenly mixed on a molecular level but still are not bonded together
Solute- substance that dissolves
Solvent- the substance that dissolves the solute
Precipitate- solid that comes back out of its solution as a result of a chemical change
Aqueous-a solution in which water is the solvent

2. Chapter 8: Substances, Mixtures, and Solubility
Substances (pg. 218)
Atoms and Elements
Substance is
matter that has the same fixed composition and properties
Cannot be broken down into simpler parts by ordinary physical processes
Only a chemical process can change a substance into one or more new substances.

3. Chapter 8: Substances, Mixtures, and Solubility
PHYSICAL PROCESSES
CHEMICAL PROCESSES
Boiling
Burning
Changing pressure
Reacting with other chemicals
Cooling
Reacting with light
Sorting

4. Chapter 8: Substances, Mixtures, and Solubility
Atoms and Elements (Pg 218
An element is an example of a pure substance; it cannot be broken down into simpler substances
The number of protons in an element are fixed; cannot be changed unless the element changes
Ex: all atoms with eight protons are oxygen atoms
Compounds
Water is an example of a substance
Always water, even when boiled or frozen
It is a compound (made of two or more elements chemically combined)
Compounds also have fixed compositions
Ratio of atoms in a compound is always the same

5. Chapter 8: Substances, Mixtures, and Solubility
Mixtures (Pg 219)
Mixtures are combinations of substances that are not bonded together and can be separated by physical processes
Ex: salt water, iron filings and sand, pulpy lemonade
Mixtures do not always contain the same proportions of the substances they are composed of.
Ex: lemonade (see example in text book)
Heterogeneous Mixtures
Heterogeneous mixture- type of mixture where substances are not mixed evenly
Ex: watermelon (fruit and seeds), cold cereal and milk

6. Chapter 8: Substances, Mixtures, and Solubility
Homogeneous Mixtures (pg. 220)
Contains two or more substances that are evenly mixed on a molecular level but still are not bonded together
Solution- another name for a homogeneous mixture
Ex: ice pops-molecules of sugar and water are evenly mixed; you cannot see the sugar.

7. Chapter 8: Substances, Mixtures, and Solubility
How Solutions Form (pg. 220)
Solute- substance that dissolves
Solvent- the substance that dissolves the solute
The substance that is present in the greatest quantity is the solvent
Forming Solids from Solutions
Crystallization- when a solute comes back out of its solution to form a solid (when solution is cooled or when some of the solvent evaporates
Crystallization is a physical change
Precipitate- solid that comes back out of its solution as a result of a chemical change
Ex: soap scum in shower

8. Chapter 8: Substances, Mixtures, and Solubility
Types of Solutions (pg. 221)
Solvent/State
Solute/State
State of Solution
Earth’s atmosphere
Nitrogen/gas
Oxygen/gas/carbon dioxide/gas argon/gas
Gas
Ocean water
Water/liquid
Salt/solid oxygen/gas carbon dioxide/gas
Liquid
Carbonated beverage
Carbon dioxide/gas
Brass
Copper/solid
Zinc/solid
solid

9. Chapter 8: Substances, Mixtures, and Solubility
Liquid Solutions (pg. 222)
In liquid solutions, the solvent is a liquid
The solute can be another liquid, a solid, or a gas
The state of the solvent usually determines the state of the solution
Liquid-gas solutions
Carbonated beverages are liquid-gas solutions
Carbon dioxide gives the beverage its fizz and some of its tartness
The beverage may contain other solutes such as the compounds that give it its flavor and color

10. Chapter 8: Substances, Mixtures, and Solubility
Liquid-liquid Solutions (pg. 222)
In liquid-liquid solutions, the solvent and solute are liquids
Ex: vinegar (95% water-solvent, 5% acetic acid-solute)
Gaseous Solutions (pg )
Small amount of one gas is dissolved in a larger amount of another gas; gas-gas solution
Ex: air we breathe is a gas-gas solution
Nitrogen is the solvent (78%) and the other gases are the solutes

11. Chapter 8: Substances, Mixtures, and Solubility
Solid Solutions (pg. 223)
In solid solutions, the solvent is a solid.
The solute can be a solid, liquid or gas
The most common solid solutions are solid-solid.
A solid-solid solution made from two metals is an alloy
It is possible to include elements that are not metals in alloys. ex: steel is an alloy that has carbon dissolved in iron

12. Chapter 8: Substances, Mixtures, and Solubility
The Universal Solvent –Water (pg. 224)
An aqueous solution is one in which water is the solvent.
Water is known as the universal solvent because it can dissolve so many solutes.

13. Chapter 8: Substances, Mixtures, and Solubility
(pg )
Molecular Compounds
Compounds that contain covalent bonds
ex: a water molecule (polar)
Ionic Bonds
Bonds between ions that are formed by the transfer of electrons.
ex: NaCl (salt) is an ionic compound

14. Chapter 8: Substances, Mixtures, and Solubility
(pg. 225)
How Water Dissolves Ionic Compounds
Properties of water: polar molecules attract negative and positive ions
ex: water dissolves table salt because its partial charges are attracted to the charged ions in the salt.
(see Figure 8 on pg. 225)

15. Chapter 8: Substances, Mixtures, and Solubility
(pg. 226)
How Water Dissolves Molecular Compounds
Water dissolves molecular compounds like sugar by moving between the different molecules of sugar, separating them.
Sugar molecules that are dissolved in water spread out until they are spaced evenly in the water.
Sugar and water are both polar.

16. Chapter 8: Substances, Mixtures, and Solubility
(pg. 226)
What Will Dissolve?
Like Dissolves Like
“like dissolves like” means that polar solvents dissolve polar solutes and nonpolar solvents dissolve nonpolar solutes
sugar + water are both polar
oil and water do not mix; oil molecules are nonpolar and water molecules are polar

17. Chapter 8: Substances, Mixtures, and Solubility
(pg. 227)
How Much Will Dissolve?
Solubility- a measurement that describes how much solute dissolves in a given amount of solvent.
Solubility of a material has been described as the amount of the material that can dissolve 100 g of solvent at a given temperature;
Highly soluble: a large amount of solute can be dissolved in 100 g of solvent.
(see examples on pg. 227)

18. Chapter 8: Substances, Mixtures, and Solubility
(pg. 227)
How Much Will Dissolve?
Solubility- a measurement that describes how much solute dissolves in a given amount of solvent.
Solubility of a material has been described as the amount of the material that can dissolve 100 g of solvent at a given temperature;
Highly soluble: a large amount of solute can be dissolved in 100 g of solvent.
Insoluble: extremely low solubility
ex: only g of barium sulfate will dissolve in 100 g of water at 25°C.
(see examples on pg. 227)

19. Chapter 8: Substances, Mixtures, and Solubility
(pg. 227)
How Much Will Dissolve?
Liquid-Solid Solutions
temperature affects the solubility of many solutes (see graph on pg. 227)
Liquid-Gas Solutions
Increase in temperature decreases solubility of a gas in a liquid-gas solution

20. Chapter 8: Substances, Mixtures, and Solubility
(pg. 228)
How Much Will Dissolve?
Saturated Solutions
saturated -solution that contains all of the solute it can hold under the given conditions.
EX: 204g of sugar in water is a saturated solution
A solution with less solute than it needs to become saturated is called an unsaturated solution.

21. Chapter 8: Substances, Mixtures, and Solubility
(pg. 228)
Rate of Dissolving
A solute dissolves faster when:
The solution is shaken or stirred
The temperature is increased
Increase in the area of contact between the solute and solvent (break up the solute into smaller pieces to increase surface area of solute that is exposed to solvent.)

22. Chapter 8: Substances, Mixtures, and Solubility
(pg. 229)
Concentration-
How much solute is present compared to the amount of solvent.
A concentrated solution has more solute per given amount of solvent than a dilute solution.
Measuring Concentration
See Applying Science (pg. 229)

23. Chapter 8: Substances, Mixtures, and Solubility
(pg. 230)
Effects of Solute Particles
All solute particles affect the physical properties of the solvent such as boiling and freezing points.
ex: NaCL and water (see pg. 230)