# Internal Assessment

Pages: 3 (700 words) Published: March 1, 2013
Narki SACKEY IB1B

Topic: Acid-Base Titration
Aims:
1. To use methyl orange and phenolphthalein as indicators to determine accurately the end of an acid-base titration. 2. To present titration data correctly.
Observations:
Table of Results Showing The Amount Of 0.12 Mol/dm3 Hydrochloric Acid Required to Neutralise 25cm3 Of Sodium Carbonate of an unknown Concentration Using Methyl Orange Indicator. Pipette Solution| Sodium Carbonate| Mol/dm3|

Burette Solution| Hydrochloric Acid| 0.12Mol/dm3|
Indicator| Methyl Orange| |
| | Trial 1| Trial 2| Trial 3|
Burette readings| Final/cm3 ± 0.05 | 14.80| 14.50| 14.60| | Initial/cm3 ±0.05| 0.00| 0.00| 0.00|
Volume Used (titre)/cm3±0.10 | | 14.80| 14.50| 14.60| Mean Titre/cm3 ±0.05| | 14.63|

* The sodium chloride and hydrochloric acid solutions were both colourless at the start of the experiment. * When methyl orange was added to the sodium chloride, it turned orange. * As the hydrochloric acid was added to the solution in the conical flask, its colour began to change to pink. * When the solution was swirled, it became orange again. At the end point, the solution turned from orange to pink. Calculations

2HCl + Na2CO3 -> 2NaCl + CO2 + H2O
Therefore, mole ratio of Hydrochloric Acid to Sodium Carbonate is 2:1 Percentage uncertainty of volume of HCl = 0.10/14.63 * 100
= 0.68% Percentage uncertainty of volume of Na2CO3 = 0.06/25 * 100
=0.24%

Number of moles of sodium carbonate = 1
Number of moles of Hydrochloric acid 2

Therefore, moles of sodium carbonate = 0.5 *0.12
= 0.6Mols Concentration of Na2CO3 = Moles of sodium carbonate
Volume of Sodium Carbonate...