1. Finding the Concentration of Ions

2. How do we determine the number of moles of each ion in a soluble compound? Steps 1)Write out the dissociation equation. (make sure it is balanced) 2)Determine the ratio of the ions ( just like the molar ratio) 3)Use your knowledge of conversions to find the information you need

3. REMEMBER There are only three numbers you use in chemistry conversions Avagadro’s number = 6.02X10 23 particles 1 mol Molar mass (periodic table) = ?g 1mol Molarity = ? mols (eg. 4M = 4 mol) 1 L 1L

4. Example 1 How many moles of Ca and Hydroxide are found in a 5g sample of Ca(OH) 2 1) Ca(OH) 2 

5. Example 1 How many moles of Ca and Hydroxide are found in a 5g sample of Ca(OH) 2 1)Ca(OH) 2  Ca +2 + 2OH -1 2)Moles produced:

6. Example 1 How many moles of Ca and Hydroxide are found in a 5g sample of Ca(OH) 2 1)Ca(OH) 2  Ca +2 + 2OH -1 2)Moles produced: For every 1 mole of Ca(OH) 2 you get 1mol Ca 2+ 2mol OH -1

7. Example 1 How many moles of Ca and Hydroxide are found in a 5g sample of Ca(OH) 2 1)Ca(OH) 2  Ca +2 + 2OH -1 2)Moles produced: For every 1 mole of Ca(OH) 2 you get 1mol Ca 2+ 2mol OH -1 3) Find the number of moles produced Ca(OH) 2 ?mol = 5g x 1mol = 0.07mol 74.0g

8. Example 1 How many moles of Ca and Hydroxide are found in a 5g sample of Ca(OH) 2 1)Ca(OH) 2  Ca +2 + 2OH -1 2)Moles produced: For every 1 mole of Ca(OH) 2 you get 1mol Ca 2+ 2mol OH -1 3) Find the number of moles produced Ca(OH) 2 ?mol = 5g x 1mol = 0.07mol 74.0g We produced Ca +2 = 1 x 0.07 = 0.07mol OH -1 = 2 x 0.07 = 0.14mol

9. REMEMBER There are only three numbers you use in chemistry conversions Avagadro’s number = 6.02X10 23 particles 1 mol Molar mass (periodic table) = ?g 1mol Molarity = ? mols (eg. 4M = 4 mol) 1 L 1L

10. Example 2 Find the number of moles of Al and O in a 12mL sample of 3M Al 2 O 3 1)

11. Example 2 Find the number of moles of Al and O in a 12mL sample of 3M Al 2 O 3 1)Al 2 O 3  2Al +3 + 3O -2

12. Example 2 Find the number of moles of Al and O in a 12mL sample of 3M (3 mol/L) Al 2 O 3 1)Al 2 O 3  2Al +3 + 3O -2 2) Moles produced: For every 1 mole of Al 2 O 3 we produce 2 moles Al +3 3moles O -2 3) ?mol =

13. Example 2 Find the number of moles of Al and O in a 12mL sample of 3M Al 2 O 3 1)Al 2 O 3  2Al +3 + 3O -2 2) Moles produced: For every 1 mole of Al 2 O 3 we produce 2 moles Al +3 3moles O -2 3) ?mol = 12mL x 1L x 3mol = 0.036mol 1000mL 1L

14. Example 2 Find the number of moles of Al and O in a 12mL sample of 3M Al 2 O 3 1)Al 2 O 3  2Al +3 + 3O -2 2) Moles produced: For every 1 mole of Al 2 O 3 we produce 2 moles Al +3 3moles O -2 3) ?mol = 12mL x 1L x 3mol = 0.036mol 1000mL 1L Moles Al +3 = 2 x 0.04mol = 0.08mol Moles O -2 = 3 x 0.04mol = 0.12mol

15. REMEMBER There are only three numbers you use in chemistry conversions Avagadro’s number = 6.02X10 23 particles 1 mol Molar mass (periodic table) = ?g 1mol Molarity = ? mols (eg. 4M = 4 mol) 1 L 1L