Chemistry Titration Essay
Honors Chemistry Titration Lab Write-up Introduction Titration Is a method, which Is meant to find the concentration of either an acid or a base by adding a measured amount of It to a known volume and concentration of an acid or Basel . Titration starts with a beaker or Erlenmeyer flask containing a very precise volume of the known concentration solution and a small amount of indicator, which is put underneath a burette containing the solution with unknown concentrations .
Small drops of the iterant are then added to the known solution and indicator until the indicator changes which means the endpoint has been reached. Single drops of the iterant can sometimes make a permanent or temporary change in the indicators. When the endpoint of the reaction is reached, the volume of reactant consumed is measured and used to calculate the concentration of solution by using the MI FL=MOVE formula which allows us to find the unknown concentration of the solutions. M represents the malarial and V represents the volume. The mall purpose of using titration Is In order to get to the end point, The end point Is defined s when the correct ratio of acid and base are mixed together to neutralize the solutions. If the quantity of the acid and base necessary to reach the end point Is equal, then the mixture is at its equivalence points.
The difference is that while the equivalence point is where you have added the right amount of solution to neutralize the solution, the end point is where the indicator actually changes colors. One scientific principle that is very common in acid-base titration is the use of indicators such as phenolphthalein.
For example, phenolphthalein is clear in acidic solutions and urns pink in neutral and basic solutions. During titration, phenolphthalein can be added to an acid. As drops of a basic solution are added, the ions and the OH- ions will combine to form waters.
As the solution gets closer to a neutral pH, the once acidic solution will start to turn pink because the phenolphthalein will change as It becomes neutral. The use of pH Indicators Is a major part of titration. Choosing the right Indicator according to equivalence point Is also a major concept.
An Indicator must be chosen based on the strength of the acid, the strength of the base, and how throng the solution will be when mixed together.
For example, if a strong acid is mixed with a strong base, then a neutral solution will form. Therefore, an indicator that changes color when the solution is neutral should be chosen. Naturalization is also a major principle. Acid-base naturalization is when an acid and base are mixed in order to form water and a salt, resulting in a neutral solution. This same thing is done in titration in order to determine the unknown concentration of the solutions.
Titration is used in many different ways in chemistry, although acid-base titration is noninsured one of the major ones. For example, titration are used in redo reactions to determine the concentrations of the guzzling agent and the reducing agent. In addition, they are also used In gas phases for determining reactive substances by reaction with an excess of another gas. Zeta potential titration uses Iso-electric points to characterize heterogeneous substances. The purpose of the experiment to HCI and Noah solution of unknown concentration.
It was predicted that if the concentration of the Noah could be determined, then that concentration could be seed to determine the concentration of the acetic acid. The methods used were acid- base titration in order to determine the volume used of the unknown concentration solution and simple multiplication and division in order to calculate the unknown concentration. Materials and Methods In order to conduct this experiment, multiple steps were followed. The burette was first rinsed with some of the Noah and all the beakers and graduated cylinders were rinsed.
Then, a 150 ml beaker and a 100 ml graduated cylinder were used to measure out 40 ml of the Noah and to add it to the burette, labeled base.
After that, 10 ml of 0. 1 M HCI were placed into the 100 ml beaker located under the beaker. 20 drops of phenolphthalein indicator were added using the dropper into this beaker and the beaker was swirled in circular motion in order to allow the indicator to mix with the acid. Next, the initial volumes for the acid and base were recorded. Then, the stopcock on the burette was slowly turned vertical so that the Noah solution would drop into the HCI, one drop at a time.
After every drop, the beaker was swirled. After the color change was evident and did not go away from being swirled, the topcoat was turned back into its horizontal position. The volume of the base utilized in order to titrate the acid was recorded using the burette. Following this, the titration formula was used to calculate the unknown concentration of Noah (in molars).
This experiment was conducted 3 times to have accurate results. After these three trials, a fourth trial was conducted using 5 ml of vinegar instead of the HCI in the beaker. The same procedure used above for the HCI and Noah titration was used for the vinegar.
The percent error calculated was 18.
9%. (Figure 2). Discussion The results found in this experiment can be summarized in the charts above. One major finding that was found in the experiment was the average concentration of the Noah solution, which was 0. MM.
This result could be found because of the properties of titration. During titration, when a strong acid and a strong base are used, the naturalization will occur when the pH is about neutral, because it has reached its equivalence point. At the equivalence point, the number of moles of acid equals the number of moles of bases.
Summary Question 2) The NV=NV formula is derived from this because Molarities multiplied by volume will give the number of moles, and because of this, the concentration of the Noah was able to be calculated. Since the equivalence point for this reaction was around a neutral pH, it was indicated when the indicator turned pink.
Phenolphthalein was used as the indicator in this experiment because it is clear in acids, and begins to turn pink around a neutral PH. The reason that methyl orange, another common indicator, was not used instead of phenolphthalein was that methyl orange is an indicator that hangers color between a pH of 3. And 4. 45. This means that it would have changed color before the equivalence point was even reached in this experiment. (Summary Question 4) Another major finding from this experiment was that the concentration of the acetic acid was 0.
MM. The reason that this was found was because the titration of the Noah and the acetic acid allowed it. In order for the vinegar to be titrated, the sodium hydroxide solution first had to be standardized. This is because in titration, one acid and one base is used . Since the concentration of the vinegar, the acid, was twine 0.
MM HCI and Noah, the concentration of the Noah was found.
With this concentration, it was made possible to use the NV=NV formula in order to calculate the concentration of the acetic acid in the vinegar. (Summary Question 1) The calculated value for the concentration of the acetic acid in the vinegar was found to be 0. 649 M. The actual accepted value for the concentration of acetic acid is 0.
8 M. The percent error calculated for this experiment was found to be 18. 9%. This shows that the value that was calculated in this experiment was about 20% wrong compared to the actual value.
The value calculated was pretty close to the actual value, and showed a difference of about 1. M. One possible source of error for this experiment could have been the fact that qualitative data was collected. As the beaker was swirled, evidence for the change to pink color was looked for. This could have impacted the results because the perception of the color pink could differ amongst different individuals. In addition, the fact that the end point is not the same as the equivalence point could have been a source of error.
Since the indicator changes color after it has reached the endpoint, t is possible that the volume recorded for the Noah could have been higher than the actual concentration.
This could have caused the calculated concentration to be smaller than it actually is. Another possible source of error could be that it is possible for the solutions to be contaminated because of prior experimentation using the same solutions. This could have impacted the data by causing the read volumes to be different from what they are supposed to be.
Based on this experiment, the results do support the hypothesis previously mentioned. The hypothesis was that if the concentration of the Noah could be determined, then that concentration could be used to determine the concentration of the acetic acid.
This was proven to be true since the concentration of the acetic acid in vinegar was found, and the answer was found to be near the accepted value. The purpose of acid-base titration is to find the concentration of an unknown acid or base, using the concentration and volume of the other and the NV=NV formula. L Since the Noah concentration was found using titration of HCI and then the acetic acid concentration was found using the concentration of Noah and titration of acetic acid, the hypothesis was correct.
Summary Questions: 3.
In order to determine the concentration of an acidic or basic solution, the concentration of the other solution must be known. Then, a proper indicator must be chosen that will indicate the equivalence point of the reaction. For example, a indicator which changes at a neutral pH would be appropriate for a strong acid and strong base. Then, the acid and the indicator should be placed under the burette, and the base should be placed in the burette. As the base is slowly dripped into the solution, the beaker should be swirled.
Once a permanent color change is evident, volume should be recorded.
Using the NV=NV formula will give the unknown molar mass of acetic acid is 60 grams. This means the weight of 0. 649 moles is 38.
94 grams. The weight of one liter of vinegar is found to be 1,000 grams, or one kilogram. (38. 94/1000)axes will give us the mass percent, which is 3. 9%.
Since it has to be at least 4% by weight acetic acid, this vinegar is very close to legal but is not. Since the calculated concentration was not exactly the accepted value, this can account for the fact that this vinegar was found to be illegal. If the accepted value was used, it would be a legal sample of vinegar.
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