1. Concentration

2. Concentrated versus Dilute
solvent
solute
Lower concentration
Not as many solute (what’s being dissolved) particles
Higher concentration
More solute (what’s being dissolved) particles

3. Concentration
Concentration – a ratio of the amount of solute dissolved over the total amount of solution.
There are several ways to show concentration – we will only focus on one

4. Quick Mole Review 1 mole = 6.02 × 1023 molecules
The molar mass of a molecule is found by adding up all the atomic masses in the atom ( from the periodic table)
Molecular mass in grams = 1 mole of that molecule

5. How many moles are in 25.5 g NaCl?
Quick Mole Example
Example:
How many moles are in 25.5 g NaCl?

6. How many moles are in 25.5 g NaCl?
Quick Mole Example
Example:
How many moles are in 25.5 g NaCl? Na Cl 1
22.99 g/mole
35.45 g/mole  = +
58.44 g/mole
1 mole NaCl molecules = g
25.5 g NaCl 1
mole NaCl
= _______ mole NaCl
0.436
58.44
g NaCl

7. Molarity
Molarity (M) is a concentration unit that uses moles of the solute over the total volume of the solution

8. Molarity Example Example:
If you dissolve 12 g of NaCl to make 150 mL of solution, what is the molarity?

9. Molarity Example = _______ mole NaCl 1.4 M NaCl
If you dissolve 12 g of NaCl in 150 mL of solution, what is the molarity? Na Cl 1
22.99 g/mole
35.45 g/mole  = +
58.44 g/mole
1 mole NaCl molecules = g
12 g NaCl 1
mole NaCl
= _______ mole NaCl
0.21
58.44
g NaCl
Remember to change mL to L! 150 mL of water = L
1.4 M NaCl

10. Dissolving substances
Substances are dissolved by a process called HYDRATION or SOLVATION
The solvent attracts to the solute
New intermolecular forces are formed
The solvent “carries off” the solute particles and surrounds the ions – keeping them dissolved!

11. Dissolving Ionic Compounds+ - O H - +
Ionic compound
water
Water molecules are polar and they attract to the charges of the ions in an ionic compound. - + -
If the ion attraction is weak enough, the water can successfully pull them apart. + - + - + -

12. Dissolving Ionic Compounds+ - O H - +
Ionic compound
water -
As more ions are “exposed” to the solvent, they can be carried off as well. + - + - + - + -

13. Dissolving Ionic Compounds+ - O H - +
Ionic compound
water + -
These free-floating ions in the solution allow electricity to be conducted - + - + - + -

14. Electrolytes
Electrolytes – substances that produce free floating ions and can conduct a current when dissolved.
Ex. NaCl(s)  Na+1(aq) + Cl-1(aq)
BaI2 
Ca3(PO4)2 
K2O 

15. Dissolving Covalent Compounds
Solvent, water (polar) + -
- +
Solute, sugar (polar)
Water forms intermolecular forces with the polar ends of the solute and “carries” the solute particles away.
- +
- +
- +

16. Dissolving Covalent Compounds
Solvent, water (polar) + -
- +
Solute, sugar (polar)
- +
NOTICE how the polar covalent molecules themselves do not split into charged ions—the solute molecule stays together and just separates from other solute molecules.

17. Non-electrolytes
NON-ELECTROLYTES - Molecules that separate from other molecules but DO NOT create free-floating ions
1 C6H12O6(s)  1 C6H12O6(aq)

18. Breaking up Electrolytes
Leave polyatomic ions in-tact (including the subscript within the polyatomic ion)
All subscripts not on a polyatomic ion become coefficients
Be sure to include charges on the dissociated ions!
Example:
Break up the following ionic compounds into their ions
KNO3
Ca(NO3)2
Na2CO3

19. Breaking up Electrolytes
Leave polyatomic ions in-tact (including the subscript within the polyatomic ion)
All subscripts not within a polyatomic ion become coefficients
Be sure to include charges on the dissociated ions!
Example:
Break up the following ionic compounds into their ions
KNO3
Ca(NO3)2
Na2CO3
 K+1 + NO3-1
 Ca NO3-1
 2 Na+1 + CO3-2

20. Let’s Practice #3 Example:
What are the molarities of the ions made in a 0.75 M solution of Ca(NO3)2

21. Let’s Practice #3 Ca(NO3)2  Ca+2 + 2 NO3-1 Ca+2 = 0.75 M
Example:
What are the molarities of the ions made in a 0.75 M solution of Ca(NO3)2
Ca(NO3)2  Ca NO3-1
For every 1 Ca(NO3)2, there will be 1 Ca+2 and 2 NO3-1 ions
Ca+2 = 0.75 M
NO3-1 = 1.5 M

22. Types of Electrolytes Strong Electrolytes Weak Electrolytes
Non-Electrolytes
Ionic compounds
Strong Acids
Strong Bases
Ionic Compounds
Weak Acids
Weak Bases
Covalent Compounds
Fully Ionize in solution
Only a few ions are created in water
No molecules separate—ions are not formed
STRONGLY CONDUCTS
CONDUCTS WEAKLY
DOESN’T CONDUCT

23. Misconceptions about dissolving
Dissolved Solids DO NOT dissappear
In the solid it is a LARGE enough particle collection to see!
After dissolving, the particles are ALONE and too small to see

24. Another Way to Think about Solutions:
Unsaturated
Saturated
Super-Saturated
More solute can be dissolved at that temperature
No more solute can be dissolved—it’s “full” at that temperature
Holds more solute than what should be dissolved at that temperature
In general, more solid will dissolve at higher temperatures!