Titration

Titration is the slow addition of one solution of a known concentration (called a titrant) to a known volume of another solution of unknown concentration until the reaction reaches neutralization, which is often indicated by a color change.

1. Titration By : Hagar Ibrahem Prof, Shimaa

2. Titration definition : Titration is the slow addition of one solution of a known concentration (called a titrant) to a known volume of another solution of unknown concentration until the reaction reaches neutralization , which is often indicated by a color change.

3. Titration Condition To be calibrated there must be several conditions including : Be a quick interaction To be a single interaction without any accompanying secondary interactions . We can fully consider it There is away we can determine the end of interaction .

4. Neutralization reaction NaOH ( aq ) + HCl ( aq ) NaCl ( aq ) + H2O

5. Titration Procedure A measured volume of an acidic or basic solution of unknown concentration is placed in a beaker. The electrodes of a pH meter are immersed in this solution, and the initial pH of the solution is read and recorded. A buret is filled with the titrating solution of known concentration. This is called the standard solution, or titrant. Measured volumes of the standard solution are added slowly and mixed into the solution in the beaker. The pH is read and recorded after each addition. This process continues until the reaction reaches the equivalence point, which is the point at which moles of H+ ion from the acid equal moles of OH- ion from the base. M A V A = M B V B

6. M A V A = M B V B M A   = Molarity of the acid V A   = Volume of the acid M B   = Molarity of the base V B  = Volume of the base

7. Examples Add 15 ml from phosphoric acid solution to 38.5 ml from sodium hydroxide solution with a concentration of 0.15 M Calculate the molocal concentration of the phosphoric acid solution if it occurs according to the following reaction H3PO4 + NaOH H2O+ NaH2PO4 H3PO4 +3 NaOH 3H2O + Na3PO4

8. Answer (M a )( 15 mL) = ( 0.15 )( 38.5 mL) Ma = 0.385 M  

9. Calculate the number of sodium hydroxide moles you need for neutralizing 0.2 mol of nitric acid Answer HNO3 + NaOH H2O + NaNO3 Nb = 0.2 moler  

10. what was concentration of the acid solution ?

11. Ma Va = Mb Vb Ma = ?? Va =20 ml na = 2 Mb = 0.0154 M Vb = 27.4 ml nb = 1 X = 0.0422 M Ba(OH)2 + HCL H2O + BaCl2 2 2    

12. Weight (gm/l) =  

13. Acid-Base Indicators Definition : A weak organic acid , that has a different color than its conjugate base, In-, with the color change occurring over a specific and relatively narrow pH range.

14. The use of an indicator is key in performing a successful titration reaction The purpose of the indicator is to show when enough standard solution has been added to fully react with the unknown concentration . However, an indicator should only be added when necessary and is dependent upon the solution that is being titrated. Therefore, indicators must only be added to the solution of unknown concentration when no visible reaction will occur . Depending on the solution being titrated, the choice of indicator can become key for the success of the titration.

15. Range of color indicator change

16. The point at which the indicator used in a titration changes color is called the end point of the titration . BUT for strong-strong titrations, the pH change is so steep and so large, that the are approximately equal.

17. Acid-Base Indicators Color on basic side Range of color change Color on acidic side Indicator Violet 0.0–1.6 Yellow Methyl violet Blue 3.0–4.6 Yellow Bromophenol blue Yellow 3.1-4.4 Red Methyl orange Yellow 4.4-6.3 Red Methyl red Blue 5.0-8.0 Red Litmus Blue 6.0-7.6 Yellow Bromothymol blue Pink 8.3-10.0 Colorless Phenolphthalein Red 10.1-12.0 Yellow Alizarin yellow

18. PH equivalence point 14.0 12.0 10.0 8.0 6.0 4.0 2.0 0.0 0.0 10.0 20.0 30.0 40.0

19. Titration Curve

20. Titration of a Strong Acid With a Strong Base Titration of a Weak Acid With a Strong Base equivalence point 14.0 12.0 10.0 8.0 6.0 4.0 2.0 0.0 0.0 10.0 20.0 30.0 14.0 12.0 10.0 8.0 6.0 4.0 2.0 0.0 40.0 equivalence point 0.0 10.0 20.0 30.0 pH

21. Titration of a Weak Base With a Strong Acid equivalence point 14.0 12.0 10.0 8.0 6.0 4.0 2.0 0.0 0.0 10.0 20.0 30.0 40.0 50.0

22. Advantages of titration There are several reasons why titration is used in laboratories worldwide: Titration is an established analytical technique. It is fast. It is a very accurate and precise technique. A high degree of automation can be implemented. Titration offers a good price/performance ratio compared to more sophisticated techniques. It can be used by low-skilled and low-trained operators. No need for highly specialised chemical knowledge.

23. Thank You