Titration : Titration
Titration : Titration Titration
Analytical method in which a standard solution is used to determine the concentration of an unknown solution. Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Titration : Equivalence point (endpoint)
Point at which equal amounts of H3O+ and OH- have been added.
Determined by…
indicator color change Titration dramatic change in pH Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Titration : Titration moles H3O+ = moles OH-
M?V? n = M?V? n M: Molarity
V: volume
n: # of H+ ions in the acid or OH- ions in the base Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Titration : Titration 42.5 mL of 1.3M KOH are required to neutralize 50.0 mL of H2SO4. Find the molarity of H2SO4. H3O+
M = ?
V = 50.0 mL
n = 2 OH-
M = 1.3M
V = 42.5 mL
n = 1 MV# = MV#
M(50.0mL)(2)
=(1.3M)(42.5mL)(1)
M = 0.55M H2SO4 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Acid-Base Titration : Acid-Base Titration
Slide 7 : Calibration Curve Acid (mL) Base (mL) 0.10 M HCl ? M NaOH 0.00 mL
1.00 mL
2.00 mL
4.00 mL
9.00 mL
17.00 mL
27.00 mL
48.00 mL 1.00 mL
1.00 mL
2.00 mL
5.00 mL
8.00 mL
10.0 mL
15.0 mL Create calibration curve of six data points
Using [HCl], determine concentration of NH3
Determine vinegar concentration using [NaOH]
determined earlier in lab Data Table
Titration Curve : Titration Curve
Slide 9 : indicator changes color
to indicate pH change e.g. phenolpthalein is colorless in acid
and pink in basic solution Pirate…”Walk the plank”
once in water, shark eats and
water changes to pink color pH endpoint equivalence
point base 7 pink colorless
Slide 10 : Calibration Curve Acid (mL) Base (mL) pH endpoint equivalence
point indicator base 7 pink - changes color to indicate pH change e.g. phenolphthalein is colorless in acid
and pink in basic solution Pirate…”Walk the plank”
once in water, shark eats and
water changes to pink color colorless
Slide 11 : Calibration Curve Acid (mL) Base (mL) pH endpoint equivalence
point indicator base 7 pink - changes color to indicate pH change e.g. phenolphthalein is colorless in acid
and pink in basic solution Pirate…”Walk the plank”
once in water, shark eats and
water changes to pink color colorless
Titration Curve : Titration Curve Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 527
Acid-Base Titrations : 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 pH Volume of 0.100 M NaOH added
(mL) Titration of a Strong Acid With a Strong Base Solution
of NaOH Solution
of NaOH Solution
of HCl Acid-Base Titrations Adding NaOH from the buret to hydrochloric acid in the flask,
a strong acid. In the beginning the pH increases very slowly. Adding additional NaOH is added. pH rises as
the equivalence point is approached. Additional NaOH is added. pH increases and then levels off as
NaOH is added beyond the equivalence point.
Slide 14 : 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 pH Volume of 0.100 M NaOH added
(mL) Titration of a Strong Acid With a Strong Base 0.00 1.00
10.00 1.37
20.00 1.95
22.00 2.19
24.00 2.70
25.00 7.00
26.00 11.30
28.00 11.75
30.00 11.96
40.00 12.36
50.00 12.52 NaOH added
(mL) pH Titration Data Solution
of NaOH Solution
of NaOH Solution
of HCl 25 mL phenolphthalein - colorless phenolphthalein - pink Bromthymol blue is best indicator: pH change 6.0 - 7.6
Titration of a Strong Acid With a Strong Base : Titration of a Strong Acid With a Strong Base 14.0 12.0 10.0 8.0 6.0 4.0 2.0 0.0 0.0 10.0 20.0 30.0 pH Volume of 0.500 M NaOH added
(mL) (20.00 mL of 0.500 M HCl by 0.500 M NaOH) Hill, Petrucci, General Chemistry An Integrated Approach 2nd Edition, page 680
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 40.0 pH Volume of 0.100 M NaOH added
(mL) Titration of a Weak Acid With
a Strong Base Titration of a Weak Acid With a Strong Base Phenolphthalein is best indicator: pH change 8.0 - 9.6
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 pH Volume of 0.100 M HCl added
(mL) Titration of a Weak Base With a Strong Acid Titration of a Weak Base With a Strong Acid 50.0
Slide 18 : 7. What is the pH of a solution made by dissolving 2.5 g NaOH in 400 mL water? Determine number of moles of NaOH x mol NaOH = 2.5 g NaOH 0.0625 mol NaOH Calculate the molarity of the solution [Recall 1000 mL = 1 L] MNaOH = 0.15625 molar NaOH Na1+ + OH1- 0.15625 molar 0.15625 molar 0.15625 molar pOH = -log [OH-] pOH = -log [0.15625 M] pOH = 0.8 pOH + pH = 14 or kW = [H+] [OH-] 1 x 10-14 = [H+] [0.15625 M] [H+] = 6.4 x 10-14 M pH = -log [H+] pH = 13.2 pH = -log [6.4 x 10-14 M] 0.8 + pH = 14
Slide 19 : What volume of 0.5 M HCl is required to titrate 100 mL of 3.0 M Ca(OH)2? x = 600 mL of 0.5 M HCl HCl H1+ + Cl1- 0.3 mol 0.3 mol 0.3 mol HCl + Ca(OH)2 CaCl2 + HOH 2 2 x mL 0.5 M 100 mL 3.0 M M1V1 = M2V2 (0.5 M) (x mL) = (3.0 M) (100 mL) x = 1200 mL of 0.5 M HCl M1V1 = M2V2 (0.5 M) (x mL) = (6.0 M) (100 mL) Ca(OH)2 Ca2+ + 2OH1- 0.3 mol 0.6 mol 0.3 mol HCl molHCl = M x L mol = (0.5 M)(0.6 L) mol = 0.3 mol HCl Ca(OH)2 mol = (3.0 M)(0.1 L) mol = 0.3 mol Ca(OH)2 [H+] = [OH-] "6.0 M"
Slide 20 : 6. 10.0 grams vinegar NaOH molNaOH = M x L mol = (0.150 M)(0.0654 L) mol = 0.00981 mol NaOH titrated with 65.40 mL of 0.150 M NaOH (acetic acid + water) moles NaOH moles HC2H3O2 = therefore, you have ...
0.00981 mol HC2H3O2 B) A) x g HC2H3O2 = 0.00981 mol HC2H3O2 0.59 g HC2H3O2 C) % = % = % = 5.9 % acetic acid Commercial vinegar is sold as 3 - 5 % acetic acid
Carboxylic Acid : Carboxylic Acid HC2H3O2 CH3COOH C2H4O2 R - COOH H C C H H O O H carboxylic acid H+ : : = acetic acid 1-
Slide 22 : H O C O C H H H Ethanol (drinking alcohol) H H Acetic acid (vinegar) O
Lactic Acid : Lactic Acid H3C C CO2H H OH Lactic acid
C3H6O3
Aqueous Acids and Bases Titration : Aqueous Acids and Bases Titration Keys Aqueous Acids and Bases Titration Aqueous Acids and Bases Titration http://www.unit5.org/chemistry/AcidBase.html
Titration : Titration ? M NaOH 1.0 M HCl titrate with 1.00 mL 2.00 mL M1 V1 = M2 V2 (1.0 M)(1.00 mL) = (x M)(2.00 mL) X = 0.5 M NaOH ? M NaOH 1.0 M H2SO4 titrate with 1.00 mL 2.00 mL M1 V1 = M2 V2 (1.0 M)(1.00 mL) = (x M)(2.00 mL) X = 0.5 M NaOH 2.0 M H1+
Titration Lab : Titration Lab Keys Determine Concentration of Vinegar http://www.unit5.org/chemistry/AcidBase.html Acids and Bases Titration Lab 2