Lab#: 10 Lab Date:
Lab Skill: MM & AI
Title:Preparation of Salt
Aim:To prepare a salt using titration
Apparatus: Conical flask, Pipette, Pipette Wooden splint, Tripod stand
filler, Burette, Filter funnel,
beakers, White Background,
Glass stirring rod, Evaporating Materials: Sodium hydroxide, Nitric acid,
dish, Bunsen burner, Wire bromophenol blue indicator
gauze,
Diagram:
Video Link method 1: https://www.youtube.com/watch?v=OFWtGyNNtGk
Video Link method 2: https://www.youtube.com/watch?v=3ysFEL4cbHk
Procedure:
1. Titration was used to determine the exact volume of nitric acid needed to neutralize sodium
hydroxide
a. The pipette was used to add 25cm3 of Sodium Hydroxide solution into a conical flask.
b. 2 drops of bromophenol blue indicator was added into NaOH. The colour of the indicator
was noted before.
c. A filter funnel was used to fill the burette to the zero mark with nitric acid solution.
d. The stop cock of the burette was opened to allow the nitric acid to run into the conical flask
e. The contents of the conical flask were swirled while mixture was observed until a permanent
colour change (yellow) occurred.
f. The stop cock of the burette was closed immediately at the first sight of a permanent colour.
(This indicated the end of reaction)
g. The volume of the nitric acid was recorded
2. The experiment was repeated by mixing the same volume of sodium hydroxide and nitric
acid
a. The pipette was used to add 25cm3 of sodium hydroxide solution into 250 mL beaker
b. A measuring cylinder was used to measure the volume of acid that was determined by the
end of the reaction and it was poured into the beaker that contained the base.
c. The contents of the beaker were stirred using a stirring rod.
3. The solution was heated to saturation.
a. The bunsen burner was connected to the gas outlet securely.
b. The bunsen burner was lit, a wire gauze and a beaker/conical flask that contained the mixture
was placed upon the tripod stand.
c. The solution was allowed to boil until almost all liquid had evaporated then the flame was
extinguished.
4. The remainder of the solution was cooled and crystallized.
5. The crystals were observed and observations were recorded
Title:TABLE SHOWING THE FINAL AND INITIAL READINGS AS WELL AS THE TOTAL
VOLUME USED TO PREPARE A SALT.
Burette Reading I II III
Final reading / cm3 4.3ml 8ml 11.7
Initial reading / cm3 0 4.3ml 8ml
Total volume used / 4.3 3.7ml 3.7ml
3
cm
Discussion:
Titration is a laboratory technique used to determine the exact amount of one substance
needed to react completely with another. It involves adding a solution of known concentration
(titrant) from a burette into a solution of unknown concentration (analyte) until a reaction
reaches completion, which is usually indicated by a color change in an indicator or a pH change.
In your experiment, nitric acid (titrant) was added to sodium hydroxide (analyte) until the
solution changed from blue to yellow, showing that neutralization had occurred.
The indicator was used to identify the end point of the titration by changing color when
neutralization occurred. At the beginning of the reaction, the bromophenol blue indicator in
sodium hydroxide solution appeared blue, indicating an alkaline solution. As nitric acid was
gradually added, the solution changed to green, showing the approach of neutralization. When
neutralization was complete, the solution turned yellow, indicating the presence of a neutral salt
solution.
The balanced chemical equation for the reaction
NaOH(aq) + HNO3 (aq) ——> NaNO3 (aq) + H2O(l)
The reaction was a neutralization reaction (acid-base reaction). The indicator was added to
visually detect the exact point of neutralization, ensuring that no excess acid or base remained.
One error was when measuring the volume of nitric acid in the burette, the reading was not
taken at eye level, causing an incorrect volume to be recorded. This would affect the accuracy of
the total acid used, leading to slight variations in the calculated endpoint of neutralization.
Conclusion:
In conclusion, the experiment successfully produced a neutral salt, sodium nitrate (NaNO₃), through
titration and evaporation.
Reflection:
I learned how to use titration to determine the exact volume of acid needed to neutralize a base and
how to obtain a pure salt through evaporation and crystallization. This method is commonly used in
laboratories and industries to prepare various salts.Neutralization reactions are useful in wastewater
treatment to balance pH levels. Sodium nitrate is used in fertilizers, glass production, and food
preservation. One way to improve the experiment is to use a pH meter instead of an indicator to
determine the endpoint more accurately. A pH meter provides precise numerical values, reducing
human error in judging the color change of the indicator.
