Title: ACID BASE TITRATION.
Objectives: 1. To determine the concentration of acid using titration. 2. Skills of titration techniques.
Apparatus: 1. 250 volumetric flask 2. 10mL measuring cylinder 3. 25mL pipette 4. 50mL burette 5. 250mL beaker 6. 150mL conical flask 7. Retord stand 8. White tile 9. Stopwatch 10. Pipette bulb
Chemicals: 1. HCl solution 2. 0.1M NaOH solution 3. H2SO4 solution 4. Distilled water 5. phenolphthalein
Introduction.
An acid-base titration is the determination of the concentration of an acid or base by exactly neutralizing the acid/base with an acid or base of known concentration. This allows for quantitative analysis of the
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In addition to the sample, an appropriate indicator is added to the titration chamber, reflecting the pH range of the equivalence point. The acid-base indicator indicates the endpoint of the titration by changing colour. The endpoint and the equivalence point are not exactly the same because the equivalence point is determined by the stoichiometry of the reaction while the endpoint is just the colour change from the indicator. Thus, a careful selection of the indicator will reduce the indicator error. For example, if the equivalence point is at a pH of 8.4, then the Phenolphthalein indicator would be used instead of Alizarin Yellow because phenolphthalein would reduce the indicator error. Common indicators, their colours, and the pH range in which they change colour are given in the table above.[14] When more precise results are required, or when the reagents are a weak acid and a weak base, a pH meter or a conductance meter are used.
Procedure. 1. 10 mL of HX is put in a volumetric flask and is diluted with distilled water and mixed through in 100mL volumetric flask. The solution is transferred into a beaker and labelled as HX. 2. The burette is rinsed with 10mL of 0.1M NaOH aqueous solution and is filled with base. 3. 25mL of HX solution is transferred into a conical flask and 2 drops of phenolphthalein are added. 4. Begin to run the base
Titration is the slow addition of one solution of a known concentration (called a titrant) to a known volume of another solution of unknown concentration until the reaction reaches neutralisation, which is often indicated by a colour change. The solution called the titrant must satisfy the necessary requirements to be a primary or secondary standard. In a broad sense, titration is a technique to determine the concentration of an unknown solution. We can use the reaction to find out the molarity of the solution by measuring the product(s) that is formed.
NH3. Add 20 mL water to the beaker by filling and emptying the 10 mL cylinder into the beaker
To start out this study the difference between acids and bases has to be identified. Acids have very low pHs and have a high concentration of hydronium ions, while bases have a high pH and have a high concentration of hydroxide ions. The difference between strong bases and acids, and weak bases and acids is the amount of dissociation. Strong bases and acids dissociate a large amount and let go of their ions in solution, while weak bases and acids may only let go of some of their ions. This is important because if the unknown solutions aren’t strong acids or bases then using their ions to calculate the pH of the solutions will give false results (Diffen 2012).
3.6.3. 2, 4 – D (2, 4–Dichloro phenoxy acetic acid) stock solution (1mg/ml): 10.0mg of 2.4-D being weighed and dissolved completely in 1N NaOH to a final total volume
When using different methods to measure pH levels there are some tools that can be useful. Some more than others but by putting into action the different methods it may determine which tools will work best and give the best results when testing the pH within a solution. The pH, which stands for the proportion of hydrogen ions in a solution, could be acidic (acidosis), neutral or basic (alkaline). The pH scale goes from numbers 1 through 14. A pH of 7 is neutral;
This is the point of stoichiometric equivalence, meaning the number of mols of both substances are equal. The mols used in the known solution can be found by multiplying the molarity by the volume used in titration. The molarity of the unknown solution can be found by dividing the number of mols, which is equal to the number of mols titrated in the known solution, by the volume in liters of the unknown solution. Titrating in this lab works because the one H+ ion in the KHP and HCl consumes and neutralizes the one OH¬- ion found in the NaOH. Standardization involves titrating the same solution multiple times to obtain an average molarity of the solution from the many
In the titration, I used these available instruments to ensure my results would be as accurate as possible.
14. Using the well D1 pipet, add two drops of the HCI to the well A1 buffer.Use a toothpick to stir the solution.
ii. The second part of the titration series involves titration of NaOH with Hydrochloric acid (HCL). Again, three reps of titration and a blank titration have to be completed. A volumetric pipet is used to measure 10.00mL of HCL into three labeled conical flasks. Then the flasks are filled with deionized water until about the 50mL mark. A buret is
The pipette was used to transfer 8 mL of the 0.5 molarity solution into the graduated cylinder. Distilled water was added to raise the bottom of the meniscus to the 20.0 mL line and the solution was transferred into the beaker after it was rinsed with the solution. The pipette was used to take a small quantity of the solution and rinse and then fill a test tube with the solution. The amount of 0.2 molarity solution needed to create 20.0 mL of 0.1 molarity solution was calculated as 10.0 mL. The pipette was used to transfer 10.0 mL of 0.2 molarity solution into the graduated cylinder and distilled water added until the bottom of the meniscus reached the 20.0 mL line. The solution was transferred to the rinsed beaker and then a portion placed into a test tube that had been rinsed with the solution. The amount of 0.1 molarity solution required to create 20.0 mL of 0.05 molarity solution was calculated to be 10.0 mL. The pipette was used to transfer 10.0 mL of 0.2 molarity solution into the graduated cylinder and distilled water added until the bottom of the meniscus reached the 20.0 mL line. The solution was then placed into a beaker that had been rinsed with the solution and then into a rinsed test
During a titration the pH of the solution will be monitored using a pH meter from that we get a titration curve. The titration curve is then used to determine the equivalent molecular weight and Ka value of the unknown weak acid, from that we are
By using acid-base titration, we determined the suitability of phenolphthalein and methyl red as acid base indicators. We found that the equivalence point of the titration of hydrochloric acid with sodium hydroxide was not within the ph range of phenolphthalein's color range. The titration of acetic acid with sodium hydroxide resulted in an equivalence point out of the range of methyl red. And the titration of ammonia with hydrochloric acid had an equivalence point that was also out of the range of phenolphthalein.. The methyl red indicator and the phenolphthalein indicator were unsuitable because their pH ranges for their color changes did not cover the equivalence points of the trials in which they were used. However, the
First, three titration curves and three second derivative curves were created to determine the average pH at the half-equivalence point from the acetic acid titrations. Titration curves were used as visuals to portray buffer capacity. The graphs and a table, Table 1, that showcased the values collected were created and included below. The flat region, the middle part, of Figures 1, 2 and 3, showed the zone at which the addition of a base or acid did not cause changes in pH. Once surpassed, the pH increased rapidly when a small amount of base, NaOH, was added to the buffer solution. Using the figures below and
The method of titration was discovered in late 1800’s by a french pioneer name Francois Antoine Henri Descroizilles. Titration is a process used to find concentration of an unknown compound. This process is used in labs to find information need in everyday life.For instance, titration is used during blood test and urine test to determine the concentration
An acid-base titration is the determination of the concentration of an acid or base by exactly neutralizing the acid/base with an acid or base of known concentration. This allows for quantitative analysis of the concentration of an unknown acid