Unit 2: Solutions

1
Solutions
PART VI Predicting solubility
2
Review..
Soluble 1g per 100 mL
Slightly/sparingly soluble between 0.1g/100mL and 1g/100mL
Insolube 0.1 g per 100 mL
3
Factors that affect solubility of ionic
substances

1. Ion charge
2. Ion size

4
1. Ion charge

• Compounds with small charges tend to soluble (and
  large charges insoluble)
• Why? The ? charge ? forces holding ions together
• Ex phosphates (PO4-3) compounds tend to be
  insoluble and alkali metals compounds (Na, K)
  tend to be soluble

5
2. Ion size

• Gaining or losing e- changes size
• Pos ions (Na) get smaller, neg ions (Cl-) get
  bigger (why? Think about shells)
• Bond b/w sm ions is stronger (closer) then lg ion
  of same charge
• Therefore, compounds with sm ions tend to be less
  soluble then lg ions
• Ex look at group 17

6
Sulfides and oxides

• Influenced by size and charge
• Tend to be insoluble because of relatively sm
  size and -2 charge

7
Using a solubility table

• Pg 286 1, 2, 3 (together)
• Pg 287 3, 4, (HW)