Lab:Titration Analysis of Hydrochloric Acid
Title
In this lab a acid-base indicator phenolphthalein was used to determine endpoint of a reaction HCl(aq) and KOH(aq). At the end point all of the HCl(aq) would have reacted with KOH(aq), and the pH becomes 7. The phenolphthalein would changed colours from colourless to pink indication when enough KOH(aq) was added. The purpose of numerous trials was to use the average volume of the 3 trials with similar measurements.
Purpose
The purpose of this lab was to use process titration to find concentration of an aqueous solution of Hcl(aq) , using KOH(aq) as the titrant.
Results
Table 1.0: Information gathered during the trial: The volume of KOH(aq),titrant, used in different trial.
Trial
1
2
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Write a discussion of error summarizing 2 sources of error, why are your results and the other group different?
The first source of error that caused different results between group was that the groups misread the colour of the indicator at exactly the equivalence point. The other group could have misjudged light pink for clear and could’ve kept pouring the titrant till the color of the indicator changed dark pink ,which will result in a higher number of moles of the solution in your buret than in your flask. The extra moles of titrant used would give incorrect measurement since the amount KOH used would to titrate HCl would increase and giving a higher concentration for HCl. To avoid this source of error groups should used pH meter instead of phenolphthalein.A pH meter giver reading from 1-14 and doesn’t require judgment. The group would know solution is basic when the reading is 7 and they would stop pouring the titrant. This would avoid extra titrant in the solution and give a more accurate concentration.
The second source of error that caused different results
Research
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
2. To titrate a hydrochloric acid solution of “known” concentration with standardized 0.5M sodium hydroxide.
3. In this analysis, an “aliquot”, (diluted fraction) of the initial solution is used for the titration. What advantage is there in diluting the original solution for the analysis?
The Distilled water pH average of HCl for zero drops was 6.67, and the pH for the final thirtieth drop
We only added a small amount of HCl to the water and sodium chloride. We did not continue to add more HCl after a significant drop in pH was recorded. We added a total of 2 mL of HCl to both H20 and NaCl before the pH changed. The 1 gram solution of sodium acetate and acetic acid changed after a 8 mL, and the other two never dropped before we reached our total of 10 mL HCl.
Whether research is experimental or developmental, there are no guarantees of perfect study processes or results, since both random and systematic errors are expected. Errors and uncertainties of a study’s outcomes surface almost every time. Faulty, aged or incorrectly calibrated instruments, during an experiment, can lead to important alterations of results. Distracting environments definitely influence the outcome. Finally, the human parameter in the sense of having ability to properly operate instruments and correctly interpret measurements definitely consist another factor of imperfect research (Bell 7-9).
Purpose: The purpose of this lab is to use the three equations of solution chemistry to determine the molarity and percent composition by weight of a solution.
To begin, three sets ofabout 0.3000g of KHP are weighed out on an analytical balance. Put the three sets of KHP into three separate, labeled flasks. All three sets of the KHP is then dissolved with approximately 50mL of deionized water. Next, a buret is used to start the actual titration. Buret is initially filled to 0.00mL mark with the NaOH solution, this is recorded as initial volume. Next, add 2-3 drops of phenolphthalein indicator into each of the three flasks containing KHP. A magnetic stir bar is then added to the first flask, and placed above a stir plate. Everything is positioned under the buret. Stirrer is put on medium speed and the titration can start. Slowly release the NaOH into the KHP flask. As the end point is reached, a pink color will be seen in the flask. When the lightest pink possible remains in the solution for more than 30 seconds titration is complete. The final volume is recorded, and the same steps are taken for the other two sets of KHP solution. Finally, blank titration is completed to determine deviation.
Its concentration was found through a quantitative and qualitative titration testing. Because HCl is acidic, a 1.07M NaOH solution was used to titrate an aqueous solution of HCl (the unknown solution). The PASCO program gave the final results shown in Figure 1. A typical titration curve can be described as starting at the initial pH of the solution, then some acid/base is added, until a sharp curve either up or down takes the pH past a neutral of 7, and towards the pH level of whatever the added acid’s/base’s pH is (Clark6). The stronger the acid or base being titrated, the faster the change occurs, which means a sharper slope of the titration graph. Also, it is important to note the equivalence point on this titration graph. At the equivalence point “the correct amount of standard solution must be added to fully react with the unknown concentration” (Xavier3). In Figure 1, this equivalence point is shown by where the sharpest slope occurs in the curve, which is seen at about a pH of 5.0
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
8. The graph for trial 3 does not match the exact graph sketched in the pre-lab as it does not accurately show the equivalence point. The curve sketched in the pre-lab reached the equivalence point when 2.00 ml of NaOH was added.
The purpose of the experiment was to compare antacids by the amounts acid they neutralize to find the most effective antacid. Finding the most effective antacid is important because it will help others by allowing them to choose the best product for their heartburn. Titration is the process of which the unknown solutions concentration reacts with a known solution concentration. During the experiment, titration was used to calculate the moles of HCl neutralized by the antacid in this case was gelusil, by knowing the moles of HCl initially added to the flask and moles of HCl neutralized by the NaOH.
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
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
For this experiment, a pH meter was used so this part of the experiment began with the calibration of the pH meter with specified buffers. The buret was then filled with the standard HCl solution and a set-up for titration was prepared. 200g of the carbonate-bicarbonate solid sample was weighed and dissolved in 100 mL of distilled water. The sample solution was then transferred into a 250-ml volumetric flask and was diluted to the 250-mL mark. The flask was inverted several times for uniform mixing. A 50-mL aliquot of the sample solution was measured and placed unto a beaker. 3 drops of the phenolphthalein indicator was added to the solution in the beaker. The electrode of the pH meter was then immersed in the beaker and the solution containing the carbonate-bicarbonate mixture was titrated with the standard HCl solution to the phenolphthalein endpoint. Readings of the pH were taken at an interval of 0.5 mL addition of the titrant. After the first endpoint is obtained, 3 drops of the methyl orange was added to the same solution and was titrated with the standard acid until the formation of an orange-colored solution. Readings of the pH were also taken at 0.5 mL addition of the titrant.