1. Solutions and pH

2. What is a Mixture? A mixture is a material compound
Mixtures are made of two or more elements or compounds that are physically mixed together but not chemically combined
Example: Earth’s atmosphere is a mixture of gases

3. A homogeneous mixture is a mixture that is uniform (the same) in composition throughout.
Example: Food coloring and water
A heterogeneous mixture is a mixture that is not uniform (the same) throughout
Example: Oil and Water

4. 3 Types of Mixtures Solution – a homogeneous mixture
Suspension – a mixture in which the particles are so large that they settle out unless the mixture in constantly stirred
Example: Sand in Water
Colloid – a mixture consisting of particles that are intermediate in size between those in solutions and those in suspensions
Example: Milk

5. What makes up a solution?
Solvent – the substance that does the dissolving in a solution
Typically present in the greatest quantity
Typically a liquid
Water is the “universal solvent”
Solute – the substance that is being dissolved in a solution
Typically present in the least amount
Typically a solid (can be a liquid)

6. Acids, Bases, and pH

7. pH Scale
The pH scale indicates the concentration of H+ ions in a solution
The pH scale ranges from 0 to 14
A pH of 7 is considered to be neutral
Water has a pH of 7
pH values below 7 are considered to be acidic
pH values above 7 are considered to be basic

8. What are acids?
An acid is any compound that forms H+ ions when in solution.
Acidic solutions have higher concentrations of H+ ions than pure water
pH < 7
The strongest acids have a pH between 1 and 3, 1 being the strongest acid
Example: Hydrochloric acid produced by the stomach

9. What are bases?
A base is a compound that produces OH- ions when in a solution.
Solutions that are basic have less H+ ions that pure water
pH > 7
Strong bases have a pH between 11-14, with 14 being the strongest

10. How is pH maintained in the human body?
The human body has a pH between
This pH must be maintained or chemical reactions that take place in the cells may not occur
Buffers are weak acids or bases that can react with strong acids or bases to maintain a relatively steady pH
Buffers help keep human blood at a pH of roughly 7