23.1 What is a solution?

1
23.1 What is a solution?

• Bottled water is a solution.
• Bottled water contains more than pure H20.
• Mineral water contains naturally present
  minerals.
• Potable water contains additives.
• Distilled water is nearly mineral-free.
• Carbonated water contains carbon dioxide gas.

2
23.1 Solutions

• A solution is a mixture of two or more substances
  that is homogeneous at the molecular level.
• The particles in a solution exist as individual
  atoms, ions, or molecules.

• A solution is a mixture of solute dissolved in a
  solvent.
• (An alloy is a solution of two or more metals.)

3
Different Solutions
4
23.1 Colloids and Suspensions

• Colloids and suspensions are NOT solutions.

5
23.1 Colloids and Suspensions

• Colloid particles are formed from clusters of
  atoms or molecules.
• Suspensions are mixtures that settle upon
  standing.
• Filtering a suspension will separate the
  different components.

6
(No Transcript)
7
23.1 What is a solution?

• Key Question
• Can you identify mixtures as solutions,
  suspensions, or colloids?

Read text section 23.1 BEFORE Investigation 23.1
8
23.2 Dissolving Rate

• Stream or lake water may contains microscopic
  parasites.
• Adding iodine tablets can kill microbes such as
  bacteria or viruses.
• How can we increase the dissolving rate of the
  tablet?

9
23.2 Dissolving Rate

• Stirring a mixture speeds dissolving.
• Stirring exposes fresh solvent to newly exposed
  solute.
• Crushing a solute table increases the surface
  area exposed to the solvent
• Every time a piece is divided the surface area
  increases.

10
23.2 Dissolving Rate

• Microencapsulation is used by pharmaceutical
  companies in time-release medicines.
• The medicines are coated with a polymer, usually
  from gelatin, silicone or cellulose.
• Varying the thickness of the coating changes the
  dissolving rate.

11
23.2 Dissolving Rate

• Key Question
• How can you influence dissolving rates?

Read text section 23.2 BEFORE Investigation 23.2
12
23.3 Solubility

• A system is a collection of matter and processes
  that take place in a certain space and can be
  observed and studied.
• Systems can be open or closed.
• A solute and solvent make up a system.

13
(No Transcript)
14
23.3 Solubility

• The term solubility means the amount of solute
  that can be dissolved in a specific volume of
  solvent under certain conditions.
• Several factors affect solubility
• chemical nature of the solvent
• the volume of solute
• temperature

15
(No Transcript)
16
23.3 Solubility of Gases

• The solubility of gases in liquids decreases as
  temperature increases.
• The solubility of a gas also depends on pressure.