Acid - Base Titration Experiment

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Experiment – Acid-Base Titration

Name: Zeinab Ossaili Date: 24th January 2011 Group: S2
Title: /[1]
Titration: Concentration of HCl/H2SO4 in NaOH
Objective: /[1]
To determine the concentration of a hydrochloric acid and sulphuric acid solution by titrating it using sodium hydroxide solution. APPARATUS AND METHOD:
Apparatus: /[1]
Dilute hydrochloric acid, dilute sulphuric acid, 0.1M sodium hydroxide, phenolphthalein indicator, graduated volumetric flask, two pipettes, burette, small filter funnel, two conical flasks, beakers, white tile, safety glasses, pipette filler, wash bottle of distilled water, small beaker and lab coat. Diagram: /[2]

Method: /[3]
1. 25 cm3 of dilute HCl were pipetted into a volumetric flask and distilled water was added until the bottom of the meniscus stopped on the graduation line. 2. The flask was then stopped and the liquids were mixed thoroughly. 3. Using the filter funnel, the diluted acid was poured into the burette and filled completely to ensure the bottom of the meniscus is on the zero line. 4. The 0.1M sodium hydroxide was collected in a small beaker and using a second pipette 25 cm3 of the alkaline solution was transferred into a conical flask. 5. A white tile was then placed under the conical flask.

6. A few drops of indicator were added to the alkali in the flask until a strong red color is produced. 7. Acid was added from the burette until the red color disappeared. This was a rough reading and will not be considered. 8. The conical flask was washed out thoroughly and the burette refilled and titration repeated but this time the acid was added slowly near the endpoint. 9. The experiment was then repeated until two accurate readings were found. 10. Steps 1-9 were repeated using dilute sulphuric acid.

11. The apparatus was washed and returned to its correct position. Health and Safety: /[2]
* Safety glasses must be worn at all times as to protect eyes in case splashing of the acid occurs. * Lab coats must not be taken off when experiment is preformed as to not ruin any clothing. * Extreme care must be taken when using the glass apparatus as to not break any of the equipment and hurt others. * The phenolphthalein indicator is very toxic and flammable hence no flame should be present. * Any spills must be reported to the instructor as soon as possible. If chemicals come in contact with skin it must be washed quickly and thoroughly.

Results Table: /[3]
Using Hydrochloric Acid:
Titration| Reading 1 (cm3)| Reading 2 (cm3)| Titre|
1 (rough)| 0| 22.8| 22.8|
2| 0| 22.7| 22.7|
3| 0| 22.6| 22.6|

Using Sulphuric Acid:
Titration| Reading 1 (cm3)| Reading 2 (cm3)| Titre|
1 (rough)| 0| 25.4| 25.4|
2| 0| 25.6| 25.6|
3| 0| 25.6| 25.6|

Calculation and Theory: /[2] * Concentration of HCl
Average Titre = (22.7 +22.6)/2 =22.65cm3
nNaOH= C x V
= 0.1 x (25/1000) = 0.0025 mol

HCl (aq) +NaOH(aq) NaCl(aq) + H2O(aq) 1 : 1

0.0025 : 0.0025
CHCl = n = 0.0025 = 0.11M
V (22.65/1000)

However; 25cm3 of the original acid was diluted to 250cm3.

Ratio 1 : 10

Number of moles 0.0025 : 0.025

MDiluted HCl= 0.025 = 1.1M
* Concentration of H2SO4
Average Titre= 25.6cm3
nNaOH = C x V
= 0.1 x (25/1000) = 0.0025 mol

H2SO4 (aq) + 2Na0H Na2SO4 (aq) +...
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