In this experiment, we will standardize acid and base solutions. It is written for wine lab workers with no background in chemistry. Perhaps a better result could have been attained if equal amounts of unknown mass were used for each trial. Due to the simple nature of the experiment it was crucial to have accurate measurements and clean equipments. Weighing contributes 2-3% error at the outset when oxalic acid is used as the standard.
The crystals required intense stirring before it could dissolved in water. Organic Chemistry, 6 th Edition; Prentice Hall: Illinois, 2011, p. The chemist expresses the concentration of a solution in various ways. Purpose: To prepare standardize solution of sodium hydroxide and to determine the concentration of unknown sulfuric acid solution. The mols of sodium hydroxide were divided by the volume of 0.
For 40 mL of 0. All the equipment was washed and gathered. Table 1 lists the molecular weights and equivalent weights of important acids and bases used in a wine laboratory. Safety is an important consideration when working with burets, acids and bases. For the Trial 1 and Trial 2, the percentage difference is 3.
It is important to note that the pink color in three titrations were all slightly different, some being darker than others. How accurately can you estimate the buret reading on a 50-mL buret that has calibration markings every 0. Similar step was taken to find the concentrations of unknown potassium hydrogen phthalate. However, this, being only 0. A funnel was placed on top of the burette, and a piece of paper was placed.
Maybe our dilution was inaccurate, or maybe the balance was not calibrated and as a result the normality of our sodium hydroxide solution is not exactly 1 N as we intended. For example, in trial 1, I used 11. However by the addition of certain organic polyhydroxy compounds it is converted to a much stronger acid which can be titrated using phenolphthalein. The pieces of glassware that were used to perform this experiment were volumetric flasks, Erlenmeyer flasks, beakers, volumetric pipette, burette, spatula and droppers. Make up to 1000 mL in a volumetric flask.
This will give you a solution approximately 0. This might have caused some deviations because the volume of sodium hydroxide added was excess. A stir bar was used during titration which could hamper with the endpoint noticed by a slight pink indication that lasts about thirty seconds so during the experiment the titration was put to an end if the pink lasted about 10 seconds. Thus the units of weight gram and volume ml are similar and interchangeable. While doing the first trail, there were continuous appearance and disappearance of light pink color. Study of analytical chemistry began in France and the first burette was made by Francois Antoine Henri Descroizilles.
Calculate the molarity of the sulfuric acid solution titrated below. That means deliberately and with respect. In this course, we will analyze commercial products such as household vinegar and bleach. Therefore it cannot be directly titrated with standard alkali. A primary standard could be any pure chemical that can be used as the initiation of a quantitative analysis. Preparation and standardization of 0.
Results The results and calculations are as follows in the next pages. It is colorless under acidic conditions and changes to a pink color under basic conditions. Finally, the experimenter should remove the clinging droplets to the neck of burette and volumetric pipette by using Kim Wipe. . Gathered all materials required 2.
Sources of Experimental Error include: The Analytical balance could give wrong reading because of the disturbance due to other students on the shelf it is placed on. The volume of the 50 mL buret used in titration was recorded to the 0. Therefore, the first persistent presence of color indicates that it is beginning to titrate the indicator and have reached the endpoint; if the solution changes to a dark pink color, the solution has overshot the endpoint. Mass error is the largest error in the experiment when using centigram balances. This reaction is one-to-one reaction on a molar basis.