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chemical practicum report

Report on Acid Base Titration Practicum

I. Experiment Number: Trial IV
II. Experiment Name: Acid-base titration: Volumetry
III. Trial Objectives:
· Studying and applying titration techniques to analyze acidic samples.
· Standardize the solution of the titrant.

IV. Basic theory
The titration of the method to determine the concentration of the known standard solution can be determined the concentration of the dititrated solution.

The acid or volumetric acid titration analysis is a quantitative analysis in which the levels of the reagent (known concentrations) compound are added to the content of the substance to be set quantitatively with the reactants. This process is often referred to as "TITRATION" and volumetric analysis is also known as "TITRIMETRI ANALYSIS".

A reagent may be used as a basis for titrimetric analysis to exert conditions for the requirements of this reaction to take place in accordance with a particular reaction, no side reactions, the reaction must take place until completely complete at the equivalence point, there must be an indicator of a point of equivalence, Takes place quickly so that titration can occur in the not-too-distant future.

The reagents used are called titran and the solution is called titer or solution. This concentration can be calculated on the basis of frozen weights by weight or by definition known as standardization or standardization.

As per the standards.
Both of these can be used to analyze a solution. Several types of reactions can be used for titration ie the deposition of oxidation-reduction reactions, acid-base reactions and complex forming reactions.
The titrimetric method can be classified according to several methods of the titration, ie based on the kinds of reactions;

Acid base titration, redox titration, settling titration, complexity titration. Based on the titrant used by acidimetry, alkalimetry, idiometry, nitrimetry, and permanganometry. Based on the concentration of the components of the test substance; Macro titrations, semi-micro titration, and micro titration. Based on the method of determining the endpoint of the titration; Visual titrations, electrometric titration, photometric titration.

In addition to the above, the solvent used is known as air-free titration (non-aqua titration). While the technical implementation is known pattern of balance titration.
In truth, if a titer of a substance whose purity is uncertain, then the concentration of the solution obtained can not be confirmed. Therefore, to express the concentration with up to four numbers means, then the tersebuit solution can be standardized.

Subsequent feeding is repeated periodically during storage. This standardization uses. In addition to that, standardization can be done by using standardized solution.
Primary is defined as a solution whose concentration can be determined by carefully weighing the substance. Primary primers must meet the following requirements easily, easily, not hygroscopically (air-related), have a high equivalent weight, purely or easily purified and its purity, The reaction with standardized substances must be stoichiometric so that the calculation basis can be achieved.

The changes in the content at the equivalent point are not clear on acid-base titration. To overcome this, an indicator is used, that is an acidic or weakly acidic organic form that has a color (color difference) with ionic color (base color), where this indicator can be color changed at a certain pH. In general, for acid-base titration, the indicator used is the phenolphthalaen indicator, which has a route of 8.3 to 10.5 where it is not colored in acidic solutions and pink in the base solution.

In this experiment, acid-base titration will be performed. Acid base titration is a substance with an acid-base reaction when as the titrant is used, it corresponds to the so-called adisymmetry. And vice versa, if the base solution as a titrant is called alkalimetry.
In summary, the acid-base reaction or neutralization by the proton (H +) of the acid is resistant to the OH-from the base. The reaction is:
H + (aq) + OH- (aq) à H2O (aq)


Some basic acidic theories; Arhenius's theory "acid basa is a substance that when dissolved into water dissociates to produce hydrogen ions as positive ions, and negative ions are hydroxy ions". Bronsted lowry theory states that acid is a substance that tends to release protons, while bases are substances that accept protons. Lewis's theory "acid is an electron acceptor while base is an electron donor". (Keenan 1979. Chemistry For University Page: 414)

The acid mixture with a base, acidic reaction with a base is called a neutralizing reaction. However, the acid equivalent mixture with a strong base alone. While the acid-base mixture involves an acid or a weak base. The reaction between strong acid and strong base can be written as the reaction of H + ion with OH-ion. In this case, the H + ion represents acid, while the OH-ion represents a base.
The pH of the solution at the time the acid and base just reacting is 7 neutral. To show the equivalence point can be used red or blue bromtimol metal indicator phenolftalaen. The indicators change color around the equivalence point. Therefore, the phenelphenalaen indicator color change is sharper (easier to observe), so the phenolphthalaen indicator is used more frequently.
(Mitchael Purba 2006. Chemistry page: 84)

The principle of acid-base titration, acid-base titration involves both acid and base as titer or titrant. Acid base titration based on neutralizing reaction. The acid solution is determined by using an alkaline solution and vice versa. The titre is added titer bit by bit until it reaches the equivalence state (meaning stoichiometry of titrant and titer just reacting). This is called the equivalent point.

In an acid-base titration method of the test solution, or a standard solution is added externally, usually from within the buret the standard solution form is determined until chemical equilibrium has been achieved with the tested secondary solution. To know when the addition of standard solution should be stopped, used a substance in the form of an indicator. The molarity calculation analysis of the solution is carried out when the equality has occurred and the process of testing the test solution is stopped.

Not all reagents can be used as titrants, for which the reagents must satisfy the following conditions to be perfect, single and according to a clear equation (theoretical basis), fast and irreversible, there is a final indication of titration (indicator), the standard solution is reacted with the apparatus Easy to obtain and simple to use, also must be stable so that the concentration is not easy to change when stored. (Ady Mara 2010. Guide to Basic Chemical Practicum I. Page: 21)


V. Tools and materials
- Buret 50 ml
- Erlenmeyer 250 ml
- Drop pipette
- Measuring cup
- Distilled water
- Indicator of phenolphthalein
- HCl 0.1 M
- 0.1 M NaOH


VI. Trial Procedure
A. Standardization of 0.1 M NaOH solution

Wash well with a 50 ml burette, then rinse with distilled water, close the spout input approximately 5 ml of standardized NaOH solution
Tilt and swivel the burette to moisten the burette surface. Remove the solution from the burette and repeat the rinsing process once or twice with NaOH solution.

Fill buret with solution up to scale 0, pass the solution to remove the air bubbles at the buret tip and buret contents again.

Wash 3 250ml erlenmeyer and then rinse with distilled water, 15 ml pipette of standard 0.1 M HCl solution into each Erlemeyer. Add to the erlenmeyer each 15 ml of distilled water and 3 drops of phenolffalein indicator.

Record the initial position of the NaOH solution on the burette and then slowly pour the NaOH solution on the first Erlenmeyer. The end point is reached when the pink color lasts for 30 seconds after mixing.

Record the final volume in buret, buret contents back and titration on second and third Erlenmeyer. Calculate Molarity of NaOH standard solution


VII. Practice Questions

1. What is an acid, a base, an equivalent point, and an indicator!
Acid is a substance with aqueous acid solution and reddening the blue litmus, reacting with the active metal to form hydrogen and neutralizing a base or a substance that can dissolve in water and give H + H + donor proton H + and electron acceptor.
· A base is a substance whose solution tastes bitter, red litmus red, feels slippery. And provide OH-ions and electron donors.
· Equivalent point is the point where the acid and base respond appropriately.
· Indicators are compounds that have different colors in the solution and this color depends on the concentration of H + ions in solution.

2. Differentiate the end point of the titration with the equivalence point!
Answer:
The difference is that the end point of the titration is where the reagent is a pH indicator when the indicator changes color. While the equivalence point is the point where the acid and base just react or acid and base just exhausted react, no reaction results and no color change indicator.


X. Discussion
Titration is a method of determining the level or concentration of a solution with other known laruatan concentration. Titration is usually distinguished by the type of reaction involved in the titration process, for example when it involves an acid-base reaction, it is referred to as acid-base titration, redox titration for titration involving oxidation reduction, complexometric titration for titration involving the formation of complex reactions and so on.

Acid base titration involves both acid and base as titer or titrant. Acid base titration based on neutralizing reaction. The acid solution is determined by using an alkaline solution and vice versa.

The titre is added titer bit by bit until it reaches the equivalent state (meaning stoichiometry of titrant and the right titer hab is reacting). This is called the equivalent point.
At the point of this equivalent point the titration process is stopped, then we record the volume of titer required to reach that state. By using the titrant volume data, volume and concentration of titer we can calculate the levels of titrant.

The end point of the titration is the state in which the reaction has proceeded with that usually characterized by visual observation through the indicator color change.

An indicator is an acidic or weakly acidic organic compound having a molecular (acidic) color different from the ionic color (base) in which the ion exhibits a color change at a certain pH. Indicators added to the solution to be titrated should be as little as possible, so the indicator does not affect the Ph solution, thus the amount of titrant required for the change of color is also minimized.

The indicator used in this experiment is phenolphthalein (PP). This indicator has a pH of 8.3 - 10.5. In this indicator acid will be colored clear, while on the base of this indicator will be pink.

Standard solution in titration plays a very important role, this is because this solution has been known to concentrate exactly. Standard solution is a chemical term indicating that a solution has been known to be concentrated.
There are two kinds of standard solutions, namely primary standard solution and secondary standard solution. The primary standard solution is a solution whose concentration is known for certainty, so it is not standardized. The characteristics of the primary standard solution are, among others, readily available, high concentration, high molecular weight, and not hygroscopic. An example of a primary standard solution is HCl.

Secondary standard solutions are concentrations of known solutions, but not yet fixed so they must be standardized again. The characteristics of secondary standard solutions are difficult to obtain, low concentration, low molecular weight, and hygroscopic. An example of a secondary standard solution is NaOH. NaOH is hygroscopic, meaning it is easy to react with air so that if it is open then it will eventually run out.

The materials used in this experiment are HCl, NaOH, water and phenolphthalein (PP). The function of HCl is as a primary standard solution that plays a role in the process of NaOH standardization. NaOH serves as a solution to be standardized. Water serves as a solvent. Phenolphthalein serves as an indicator that determines discoloration.

The analysis used in this experiment is qualitative analysis and quantitative analysis. Qualitative analysis is used when we observe the process of color change in the titrated solution. While quantitative analysis is used when we calculate the standardized solution concentration based on the data from the experimental results.

The acid-base theory according to Arrhenius is that acid is a substance that in water produces H + ions. While the base is a substance that in the water produces OH-ions.
The acid-base theory according to Bronsted-Lawry is acid is a substance that gives proton or H + proton donor. While a base is a substance that accepts proton or acceptor of OH-proton.

Lewis's acid-base theory is that acid is a substance that accepts or accepts electrons. While the base is a substance that gives or electron donors.


XI. Conclusion
1. Titration is a method used to determine the concentration of an acid-base solution.
2. Acid base titration is a volumetric method, to determine the acid-base concentration.
3. Indicators are compounds that have different colors in the solution and this color depends on the concentration of H + ions in the solution.
4. The end point of the titration is the end point where the reagent is an indicator or pH when the indicator changes color.
5. Equivalent point is the point where the acid and base exactly react, no reaction result and no color change indicator.


BIBLIOGRAPHY

Keenan. 1979. Chemistry For University. Jakarta: Erland.
Mara, Ady. 2010. Guide to Basic Chemical Practicum I. Inderalaya: University
Sriwijaya.
Purba, Mitchael. 2006. Chemistry. Jakarta: Erland.