acid-base titrations. simulation: //users.skynet.be/eddy/titratie.swf strong acid/ strong base
TRANSCRIPT
![Page 1: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/1.jpg)
Acid-base titrations
![Page 2: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/2.jpg)
Simulation: http://users.skynet.be/eddy/titratie.swfStrong acid/ strong base
![Page 3: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/3.jpg)
pH curvespH curves
Types There are four types of acid-base titration; each has a characteristic curve.
strong acid (HCl) v. strong base (NaOH) weak acid (CH3COOH) v. strong alkali (NaOH)
strong acid (HCl) v. weak base (NH3)
weak acid (CH3COOH) v. weak base (NH3)
In the following examples, alkali (0.1M) is added to 25cm3 of acid (0.1M)
End points need not be “neutral‘ due to the phenomenon of salt hydrolysis
![Page 4: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/4.jpg)
Equivalence point: the point at which sufficient base has been added to just neutralise the acid (or vice-versa).
![Page 5: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/5.jpg)
strong acidstrong acid (HC (HCll) ) v. strong base v. strong base (NaOH)(NaOH)
![Page 6: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/6.jpg)
pH 1 at the start due to 0.1M HCl
(strong monoprotic acid)
strong acidstrong acid (HC (HCll) ) v. strong base v. strong base (NaOH)(NaOH)
![Page 7: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/7.jpg)
Very little pH change during the initial 20cm3
pH 1 at the start due to 0.1M HCl
(strong monoprotic acid)
strong acidstrong acid (HC (HCll) ) v. strong base v. strong base (NaOH)(NaOH)
![Page 8: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/8.jpg)
Very little pH change during the initial 20cm3
Very sharp change in pH over the addition of less than half a drop of NaOH
pH 1 at the start due to 0.1M HCl
(strong monoprotic acid)
strong acidstrong acid (HC (HCll) ) v. strong base v. strong base (NaOH)(NaOH)
![Page 9: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/9.jpg)
Very little pH change during the initial 20cm3
Very sharp change in pH over the addition of less than half a drop of NaOH
Curve levels off at pH 13 due to excess 0.1M NaOH
(a strong alkali)
strong acidstrong acid (HC (HCll) ) v. strong base v. strong base (NaOH)(NaOH)
pH 1 at the start due to 0.1M HCl
(strong monoprotic acid)
![Page 10: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/10.jpg)
Very little pH change during the initial 20cm3
Sharp change in pH over the addition of less than
half a drop of NH3
Curve levels off at pH 10 due to excess 0.1M NH3
(a weak alkali)
pH 1 at the start due to 0.1M HCl
strong acidstrong acid (HC (HCll) ) v. weak basev. weak base (NH (NH33))
![Page 11: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/11.jpg)
Steady pH change
Sharp change in pH over the addition of less than
half a drop of NaOH
Curve levels off at pH 13 due to excess 0.1M NaOH
(a strong alkali)
pH 4 due to 0.1M CH3COOH (weak monoprotic acid)
weak acid weak acid (CH(CH33COOH) COOH) v. strong basev. strong base (NaOH) (NaOH)
![Page 12: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/12.jpg)
weak acidweak acid (CH (CH33COOH) COOH) v. weak basev. weak base (NH (NH33))
Types
Steady pH change
pH 4 due to 0.1M CH3COOH (weak monoprotic acid)
NO SHARPCHANGE IN pH
Curve levels off at pH 10 due to excess 0.1M NH3
(a weak alkali)
![Page 13: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/13.jpg)
4.3 exercise 4
![Page 14: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/14.jpg)
Other pH curves - Other pH curves - acid v. carbonate
Sodium carbonate reacts with hydrochloric acid in two steps...
Step 1 Na2CO3 + HCl ——> NaHCO3 + NaCl
Step 2 NaHCO3 + HCl ——> NaCl + H2O + CO2
Overall Na2CO3 + 2HCl ——> 2NaCl + H2O + CO2
![Page 15: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/15.jpg)
Other pH curves - Other pH curves - acid v. carbonate
There are two sharp pH changes
The second addition of HCl is exactly the same as the first because the number of moles of HCl which react with the NaHCO3 is the same as that reacting with the Na2CO3.
17.50cm3 35.00cm3
Sodium carbonate reacts with hydrochloric acid in two steps...
Step 1 Na2CO3 + HCl ——> NaHCO3 + NaCl
Step 2 NaHCO3 + HCl ——> NaCl + H2O + CO2
Overall Na2CO3 + 2HCl ——> 2NaCl + H2O + CO2
![Page 16: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/16.jpg)
Other pH curves - Other pH curves - polyprotic acids (Hpolyprotic acids (H33POPO44))
Phosphoric acid is triprotic; it reacts with sodium hydroxide in three steps...
Step 1 H3PO4 + NaOH ——> NaH2PO4 + H2O
Step 2 NaH2PO4 + NaOH ——> Na2HPO4 + H2O
Step 3 Na2HPO4 + NaOH ——> Na3PO4 + H2O
![Page 17: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/17.jpg)
Other pH curves - Other pH curves - polyprotic acids (Hpolyprotic acids (H33POPO44))
There are three sharp pH changes
Each successive addition of NaOH is the same as equal
number of moles are involved.
Phosphoric acid is triprotic; it reacts with sodium hydroxide in three steps...
Step 1 H3PO4 + NaOH ——> NaH2PO4 + H2O
Step 2 NaH2PO4 + NaOH ——> Na2HPO4 + H2O
Step 3 Na2HPO4 + NaOH ——> Na3PO4 + H2O
![Page 18: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/18.jpg)
Other pH curves - Other pH curves - polyprotic acids (Hpolyprotic acids (H33POPO44))
pH of H3PO4 = 1.5
Phosphoric acid is triprotic; it reacts with sodium hydroxide in three steps...
Step 1 H3PO4 + NaOH ——> NaH2PO4 + H2O
Step 2 NaH2PO4 + NaOH ——> Na2HPO4 + H2O
Step 3 Na2HPO4 + NaOH ——> Na3PO4 + H2O
![Page 19: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/19.jpg)
Other pH curves - Other pH curves - polyprotic acids (Hpolyprotic acids (H33POPO44))
pH of NaH2PO4 = 4.4
pH of H3PO4 = 1.5
Phosphoric acid is triprotic; it reacts with sodium hydroxide in three steps...
Step 1 H3PO4 + NaOH ——> NaH2PO4 + H2O
Step 2 NaH2PO4 + NaOH ——> Na2HPO4 + H2O
Step 3 Na2HPO4 + NaOH ——> Na3PO4 + H2O
![Page 20: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/20.jpg)
Other pH curves - Other pH curves - polyprotic acids (Hpolyprotic acids (H33POPO44))
pH of Na2HPO4 = 9.6
pH of NaH2PO4 = 4.4
pH of H3PO4 = 1.5
Phosphoric acid is triprotic; it reacts with sodium hydroxide in three steps...
Step 1 H3PO4 + NaOH ——> NaH2PO4 + H2O
Step 2 NaH2PO4 + NaOH ——> Na2HPO4 + H2O
Step 3 Na2HPO4 + NaOH ——> Na3PO4 + H2O
![Page 21: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/21.jpg)
Other pH curves - Other pH curves - polyprotic acids (Hpolyprotic acids (H33POPO44))
pH of Na3PO4 = 12
pH of Na2HPO4 = 9.6
pH of NaH2PO4 = 4.4
pH of H3PO4 = 1.5
Phosphoric acid is triprotic; it reacts with sodium hydroxide in three steps...
Step 1 H3PO4 + NaOH ——> NaH2PO4 + H2O
Step 2 NaH2PO4 + NaOH ——> Na2HPO4 + H2O
Step 3 Na2HPO4 + NaOH ——> Na3PO4 + H2O
![Page 22: Acid-base titrations. Simulation: //users.skynet.be/eddy/titratie.swf Strong acid/ strong base](https://reader033.vdocument.in/reader033/viewer/2022061404/56649efe5503460f94c1354b/html5/thumbnails/22.jpg)
Page 50, Question 4a), 4bi, 4bii