1. Review from Monday 5/5Review from Monday 5/5 MolarityMolality  (m)  The amount of substance of solute, divided by the mass of solvent.  The number of moles of solute divided by the number of kilograms of solvent  Moles of solute = mol Kg of Solution kg  (M)  Describes the amount of solute in moles and the volume of the solution in liters.  The number of moles of solute per volume of solution in Liters  Moles of Solute = mol Liters of Solution L

2. Types of solutionsTypes of solutions  Solution-a homogeneous mixture  Solvent-the largest substance that is present within the solution  Solutes-the smallest substance within the solution  Aqueous solution-solutions with water as a solvent  Saturated-a solution that contains as much solute as will dissolve at the temperature  Unsaturated- a solution that has not reached the limit of solute that will dissolve  Concentrated-a large amount of solute dissolved  Dilute-a relatively small amount of solute is dissolved  Supersaturated- a solution that contains more dissolved material than could be dissolved by the solvent under normal circumstances

4. Acids  Produce hydrogen ions  H + or HA  Taste sour  pH less than 7 Bases  Produce hydroxide ions  OH - or A -  Taste Bitter  pH greater than 7

5. Brønsted-Lowery ModelBrønsted-Lowery Model  Acid is a proton (H + ) donor, and a base is a proton acceptor  The new acid that is formed is the conjugate acid and the new base is the conjugate base i.e. HA(aq) + H 2 O(l)  H 3 O + (aq) + A - (aq) Acid base conjugate acid conjugate base

6. Arrhenius Acids and BasesArrhenius Acids and Bases  Acids-dissociate in water to produce hydrogen ions[H + ]  Bases-dissociate in water to produce hydronium ions [H 3 O + ]

7. Strong AcidsStrong Acids  Forward reaction predominates  A - is a much weaker base than H 2 O  When there is a strong acid, we say that HA has completely ionized or dissociated. i.e. HA(aq) + H 2 O(l)  H 3 O + (aq) + A - (aq) *HA is the strong acid Common strong acids include: HCl, HNO 3,HClO 4 and H 2 SO 4

8. Weak AcidsWeak Acids  Reverse reaction predominates  A - is much stronger base than H 2 O I.E. HA(aq) + H 2 O(l)  H 3 O + (aq) + A - (aq) Now A - has a much more attraction to H + molecules than the H 2 O

9. Diprotic AcidsDiprotic Acids  An acid that has two protons  Example: H 2 SO 4

10. pH ScalepH Scale  Acids- 0.1-6.99  Bases-7.01-14  Neutral 7---H 2 O

11. Calculating pH and pOHCalculating pH and pOH pH  Need to know Molarity. Then calculate using the expression: pH=-log[H 3 O + ]  Using the hydronium ion to calculate pH use the expression: 10 -pH pOH  Need to know Molarity. Then calculate using the expression: pOH=-log[H 3 O + ]  Using the hydronium ion to calculate pOH use the expression: 10 -pOH

12. The relationship between pH and pOH  pH + pOH = 14  For example:  A solution has a pOH of 11.76. What is the pH of this solution?  14- pOH = pH  14-11.76= 2.24

13. Examples  Find the pH of a 0.0025M HCl solution. The HCl is a strong acid and is a 100% ionized in the H 2 O. The hydronium ion is 0.0025M.  pH=-log(0.0025M)=-(2.60)=2.60

14. Example  What is the hydronium ion concentration in a solution that has a pOH of 5.70?  [OH - ]=10 -5.70 =2.00 x 10 -6 M

15. Neutralization reactionsNeutralization reactions  In chemical reaction an acid and base react to form a salt.  They are often exothermic reactions  pH is not necessarily 7, could/can vary based on the strengths of the acids and bases  Example:  HCl + NaOH  NaCl + H 2 O

16. Amphoteric substancesAmphoteric substances  Substances that behave as both acids and bases  Examples: ZnO  Acid: ZnO + 2H +  Zn 2+ + H 2 O  Base: ZnO + H 2 O + 2OH -  [Zn(OH) 4 ] 2-

18. Equilibrium  Equilibrium-is the exact balancing of the two processes, one of which is the opposite of the other.  Equilibrium rate occurs when the rate of evaporation exactly equals the rate of condensation

19. Reaction ratesReaction rates  Activation energy (E a )- is the minimum energy needed for a reaction to occur  Catalyst- a substance that speeds up the reaction without being consuming.

20. Le Châletier’s principleLe Châletier’s principle The effect of a change in concentration:  When a reactant or product is added to a system at equilibrium, the system shifts away from the added component. On the otherhand, if a reactant or product is removed, the system shifts toward the component. The effect of a change in temperature:  Treat energy as a reactant (endothermic) or as a product (exothermic) and predict the direction of the shift as you would for concentration. The effect of a change in volume:  The system shifts in the direction that gives the smaller number of gas molecules  Adding a catalyst has no effect on the position of the equilibrium