1. Solutions and Suspensions

2. Objective:
To describe the unique properties of water and how these properties support life on Earth

3. How does water’s polarity influence its properties as a solvent?
Water’s polarity gives it the ability to dissolve both ionic compounds and other polar molecules
Watch the animation of a crystal of table salt dissolving in a glass of water
Sodium and chloride ions on the surface of the salt crystal are attracted to the polar water molecule
Ions break away from the crystal and gradually become dispersed in the water

4. How does water’s polarity influence its properties as a solvent?
A solution is formed, which is one of two types of mixtures
Mixture Solution Suspension
Physical combination of two or more substances
Mixture that has evenly distributed particles
Mixture with non-dissolved particles

5. Water molecules sometimes split apart to form ions
In pure water, this happens about 1 in 550 million water molecules
H2O H+ + OH-
Water hydrogen ion hydroxide ion
More H+ forms acid in solution
More OH- forms base in solution

6. Acids, Bases, and pH
Chemists devised a measurement system called the _________ to indicate the concentration of H+ ions in solution
pH scale

7. Why is it important for cells to buffer solutions against rapid changes in pH?
The pH scale ranges from __________
A solution below a pH of 7 is __________
A solution above a pH of 7 is ___________
Pure water has a pH of ____ and is neutral
Each movement from one number to the next increases or decreases the H+ ion concentration by 10
acidic
basic 7

9. Why is it important for cells to buffer solutions against rapid changes in pH?
The pH of fluids in most cells of the human body are between 6.5 and 7.5
If the pH is lower or higher, it will affect the chemical reactions that occur within the cells
Controlling the pH is important for maintaining ___________, which is done through dissolved compounds called ________
homeostasis
buffers