1. REACH will present significant challenges to all of us
REACH will present significant challenges to all of us. There’s still much water to flow under the bridge before the detailed requirements of REACH are set in tablets of stone.
However, there is one thing we can anticipate and that is that REACH will demand much greater supply chain co-operation on the use of chemicals.
From the chemical manufacturer, through the formulator, to the product manufacturer to the final retailer we will all have to work together far more, understand each others challenges, languages and contribution to a mutual value chain.
Today we want to share with you some ideas about how such partnerships can work. We don’t offer a panacea, nor do we imagine that our relationship is necessarily representative of those that you in this room may have, but we feel much of the learning from our experience can be interpreted constructively in your supply chains.

2. Strong Base to Weak Acid
Acid-Base Titrations
Strong Base to Weak Acid
Consider adding a strong base (e.g. NaOH) to a solution of a weak acid (e.g.KHP).

3. Strong Acid-Base Titrations
The plot of pH versus volume during a titration is a titration curve.

4. Weak Acid-Strong Base Titrations
Acid-Base Titrations
Weak Acid-Strong Base Titrations

6. Problem
What is the pH of a solution prepared by mixing exactly 30.0 ml of M HC2H3O2 with 15.0 ml of M KOH.

7. Strong acid: [H3O+] = concentration of acid
so: pH = -log [H3O+] = -log[acid]
Weak Acid: one must calculate the [H3O+] from an equilibrium ionization expression.
HA + H2O  H3O+ + A-
Ka = _ [H3O+][A-]
[HA]
These are equilibrium concentrations.

8. Starting pH, only acid and water.
25.0 mL of 0.10M Acetic acid Ka=1.8 x 10-5
Some base has been added 2 4 3
This is also the “buffer region” 1.
pKa = pH at this point (halfway point) 1.
Starting pH, only acid and water.
0.10 M NaOH

9. Approximations:
[H+][A-] 4 2
pOH=-Log[OH-] 3
[OH-]=[HA]
[H+]=[A-] 1

10. 2. 4 3 1. 25.0 mL of 0.10M Acetic acid Ka=1.8 x 10-5
Some base has been added
This is also the “buffer region” 4 3
pKa = pH at this point (halfway point) 1.
0.10 M NaOH

14. The color change of the indicator bromthymol blue
basic
change occurs over ~2pH units
acidic

15. Curve for a strong acid-strong base titration
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16. Strong Acid-Strong base Titration
pH starts low and increases gradually as acid is neutralized by the added base
Close to equivalence point pH rises steeply
Beyond this, pH increases slowly with addition of more base
Equivalence point
the mol OH1- = mol H1+
The pH = 7

17. Curve for a weak acid-strong base titration
Titration of 40.00mL of M HPr with M NaOH
Curve for a weak acid-strong base titration
pH = 8.80 at equivalence point
pKa of HPr = 4.89
methyl red
[HPr] = [Pr-]

18. Curve for a weak base-strong acid titration
Titration of 40.00mL of M NH3 with M HCl
pKa of NH4+ = 9.25
Curve for a weak base-strong acid titration
pH = 5.27 at equivalence point

19. Curve for the titration of a weak polyprotic acid.
pKa = 7.19
pKa = 1.85
Titration of 40.00mL of M H2SO3 with M NaOH