1. Acid-Base Reactions

2. Neutralization Reactions
Type of acid-base reaction
Strong Acid + Strong Base----all OH- ions combine with H+ ions to give water molecules
Produce water and a SALT, MX. A salt is an ionic compound.
HX MOH  MX H2O
ACID + BASE  SALT + WATER
Antacid analogy….chewing TUMS to help with acid reflex. The basicity of TUMS neutralizes stomach acid.
Neutralization Reactions “neutralize” the acid and base in the reaction.

3. NaOH(aq) + HCl(aq)  NaCl(aq) + H2O(l)
Example 1:
NaOH(aq) + HCl(aq)  NaCl(aq) + H2O(l)
What are the spectator ions?
What is the net ionic equation?

4. NaOH(aq) + HCl(aq)  NaCl(aq) + H2O(l)
Example 1: continued
NaOH(aq) + HCl(aq)  NaCl(aq) + H2O(l)
Na+(aq)+ OH-(aq) + H+(aq)+ Cl-(aq)  Na+(aq)+ Cl-(aq)+ H2O(l)
What are the spectator ions?
Na+ and Cl-
What is the net ionic equation?
OH-(aq) + H+(aq)  H2O(liq)----always with strong acids and bases

5. Salts Ionic compounds Formed using cation from base and anion of acid
Can have acidic or basic properties if one acid/base component is strong and the other is weak.
Examples: NaCl, Na2SO4, MgCl2
Antacid analogy….chewing TUMS to help with acid reflex. The basicity of TUMS neutralizes stomach acid.
Neutralization Reactions “neutralize” the acid and base in the reaction.
Give example:

6. Example 2:
Predict the products from the acid-base reaction between H2CO3 + Sr(OH)2
Write the complete, balanced equation as well as the net-ionic equation.
Complete equation: H2CO3 + Sr(OH)2  SrCO H2O
Net-ionit equation: H+ + OH- --- H2O

7. Practice!
Complete and balance the following acid-base reactions. Write the net-ionic equation as well:
HClO4 + NaOH 
2) HBr + Ba(OH)2 
3) HNO3 + KOH 
4) Ca(OH)2 + HNO3 
5) Mg(OH)2 + HCl 

8. What are acid-base indicators?
Contains a weak acid and its conjugate base
Weak acid—one color
Conjugate base—different color
Changes color based on what solution (acidic or basic) it is placed in.
Change color over a specific pH range –transition interval
Used when specific pH measurements not needed, seen a lot with titrations

9. Common Indicators Phenolphthalein Litmus indicator Broad pH range
Dye originating from lichens
pH < 4.5 (red), pH > 8.3 (blue)

10. Buffers
A mixture composed of a weak acid and its conjugate base OR weak base and its conjugate acid
buffers” or reduces the affect of a change in the pH of a solution
Absorbs slight changes in pH resulting from the addition of small acid/base amounts to water.
Buffer capacity—
indicates how much strong acid/base can be tolerated in a buffer solution before pH changes
Trait of buffer
Mixture allows both a weak acid and weak base to be present in solution—maintains pH
-so if strong acid added, the acid reacts with the weak conjugate base in an acidic buffer
-if a strong base added, the base reacts with the weak acid in an acidic buffer –keeps H+ and OH- ions from increasing to a point (only small amounts)
-concentrations of weak acid and CB > amt. of base or acid added to maintain pH

11. Types of buffers Acidic Buffers Basic Buffers
Formed from mixing a weak acid and its conjugate base
pH < 7
Basic Buffers
Formed from mixing a weak base and its conjugate acid
pH > 7

12. Why are buffers important to us?
Buffers present in our body keep fluids within a certain pH range.
Blood has a pH range of approximately
A buffer involving H2CO3/HCO3- maintains the blood pH
This pair is carbonic acid/hydrogen carbonate ion
Buffers help keep fluids in our body at a certain pH range—buffers present in our body
-Increase blood pH—alkalosis (base)
-Decrease blood pH--acidosis

13. Homework:
Additional pH calculations worksheet