Standardization of Sodium Hydroxide Solution

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Abstract.

This report is about how to standardize a Sodium Hydroxide (NaOH) solution by titrating it with pure sample of Potassium acid Phthalate (KHC8H4O4). This experiment has two sections. The first section is to standardize the Sodium Hydroxide by titration. Three sample of 0.7 – 0.9 g of solid KHP are place into each of the three numbered Erlenmeyer flasks. 50 ml of distilled water are added to each three of it from graduated cylinder and constantly shake it until the KHP solution are completely dissolve. 2 drops of phenolphthalein are add to each flask. Titrate each of the three flasks simultaneously with NaOH solution to the end point with the first appearance of a faint light pink that persist for 15 seconds. The colour will fade as CO2 from the air are dissolve in the solution. The second section is about standardization of diluted Sodium Hydroxide (NaOH). These sections are quite similar to section 1 but this method is titrating using a diluted Sodium Hydroxide which is diluted for 5 times. The rest of the experiment for section 2 is similar to section 1.

Objective:
* To standardize the sodium hydroxide solution with potassium hydrogen phthalate by using titration technique. * To calculate the concentration of the standard solution after titration is complete.

Materials:
100 mL Erlenmeyer Potassium Hydrogen Phthalate, KHP
50 mL Graduated cylinderDistilled Water
Titration Set Up Spatula
Burette Top loading balance ± 0.01g
50 % w/w NaOH

Procedure:
1. Standardization of sodium hydroxide (NaOH).
i. Three samples of solid KHP were weighed accurately of about 0.7 g to 0.9 g into each of the three clean, numbered Erlenmeyer flasks. ii. Each flasks were added 50 ml of distilled water from a graduated cylinder and the flask were shaken gently until the KHP is dissolved. Then 2 drops of phenolphthalein were added into each of the flask. iii. Each of them were titrated with the NaOH solution to the end point with the first appearance of a faint (light) pink color that persists for 15 second. The color faded as CO2 from the air dissolved in the solution. iv. The average molarity, the standard deviation and relative standard deviation (S/X) was calculated.

2. Standardization of Diluted NaOH
i. A diluted standardization NaOH were prepared in a 250 mL volumetric flask. ii. Three samples of solid KHP were weighed accurately of about 0.7 g to 0.9 g into each of the three clean, numbered Erlenmeyer flasks. iii. Each flasks were added 50 ml of distilled water from a graduated cylinder and the flask were shaken gently until the KHP is dissolved. Then 2 drops of phenolphthalein were added into each of the flask. iv. Each of them were titrated with the NaOH solution to the end point with the first appearance of a faint (light) pink color that persists for 15 second. The color faded as CO2 from the air dissolved in the solution. v. The average molarity, the standard deviation and relative standard deviation (S/X) was calculated.

Data.

1. Standardization of Sodium Hydroxide (NaOH) solution.
| Trial 1| Trial 2| Trial 3|
Mass of KHP (g)| 0.85| 0.80| 0.80|
Final burette reading, NaOH (ml)| 14.1| 26.80| 39.40| Initial Burette reading, NaOH (ml)| 0.0| 14.10| 26.80| Volume of NaOH (ml)| 50| 50| 50|
Molarity of NaOH (M)| 0.00028| 0.00031| 0.00031|
Average molarity of NaOH, (M)| 0.0003|
Standard deviation, σ| 1.732 x 10-5|

2. Diluted Standardization of Sodium Hydroxide (NaOH) solution. | Trial 1| Trial 2| Trial 3|
Mass of KHP (g)| 0.80| 0.80| 0.84|
Final burette reading, NaOH (ml)| 66.20| 128.30| 191.80| Initial Burette reading, NaOH (ml)| 0.00| 66.20| 128.30| Volume of NaOH (ml)| 66.20| 62.10| 63.50|
Molarity of NaOH (M)| 0.000059| 0.000063| 0.000062| Average molarity of...
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