Chemistry: Acid-Base Titration

2. To titrate a hydrochloric acid solution of “known” concentration with standardized 0.5M sodium hydroxide.

24) Separate the formed crystals (benzoin) and allow them to dry, then take the MP.

The problem that was trying to be solved in this study deals with analyzing unknown solutions. In this particular case, a chemical company has several unknown solutions and to correctly dispose of them they need to know their properties. To figure out the properties several qualitative tests were performed throughout the study (Cooper 2012).

Three grams of a mixture containing Benzoic Acid and Naphthalene was obtained and placed in 100 ml beaker and added 30 ml of ethyl acetate for dissolving the mixture. A small amount (1-2 drops) of this mixture was separated into a test tube. This test tube was covered and labelled as “M” (mixture). This was set to the side and used the following week for the second part of lab. The content in the beaker was then transferred into separatory funnel. 10 ml of 1 M NaOH added to the content and placed the stopper in the funnel. In the hood separatory funnel was gently shaken for approximately one minute and vent the air out for five seconds. We repeated the same process in the same manner one more time by adding 10ml of 1M NaOH.

2. Calculate the molarity of the Hydrochloric acid in the flask. You may refer to the Titration demo at the beginning of the honors lesson, just above the Virtual Lab to see sample calculations.

Fill a test tube about 1/3 full with cold tap water for use in step 34.

with 15 % KOH. Be sure not to get the KOH on the sides of the respirometer. Then place a small wad of non-

Chemistry 102 is the study of kinetics – equilibrium constant. When it comes to the study of acid-base, equilibrium constant plays an important role that tells how much of the H+ ion will be released into the solution. In this lab, the method of titrimetry was performed to determine the equivalent mass and dissociation constant of an unknown weak monoprotic acid. For a monoprotic acid, it is known that pH = pKa + log (Base/Acid). When a solution has the same amount of conjugate base and bronsted lowry acid, log (Base/Acid) = 0 and pH = pKa. By recording the pH value throughout the titration process and determining the pH at half- equivalence point, the value of Ka can be easily calculated. In this experiment, the standardized NaOH solution has a concentration of 0.09834 M. The satisfactory sample size of known B was 0.2117 g. The average equivalent mass of the unknown sample was found to be 85.01 g, pKa was found to be 4.69, which was also its pH at half-equivalence point and Ka was found to be 2.0439×〖10〗^(-5). The error was 1.255% for equivalent mass and 0.11% for Ka. In other word, the experiment was very precise and accurate; the identity of the unknown sample was determined to be trans-crotonic by the method of titrimetry.

Was the pH level always within the “normal” range for the human body? Yes it was.

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, we started testing solutions such as Water, Sodium Phosphate (Buffer), and Sodium Chloride. The two control solutions that were used in experiment were HCl which is an acid and NaOH which is a base. The purpose of the two controls is to test and determine if NaCl is a buffer or not. When HCl was added to NaCl the pH decreased from 7.60 to 2.53 pH. The comparison of the pH change of NaCl and Na3PO4, shows that when adding acid to Na3PO4, pH did not change dramatically as it did with NaCl, only decreased from 9.30 pH to 8.73 pH. Comparing the pH changes of water and NaCl, the results seems that both have dramatic decrease in the pH level. The results shows that NaCl acted more as a water because when HCl was added, the pH dropped from

The pH of a solution is the measure of the concentration of charged Hydrogen ions in that given solution. A solution with a pH lower than seven is considered to be acidic. A solution with a higher pH is a base. It is very important for organisms to maintain a stable pH. Biological molecules such as proteins function only at a certain pH level and any changes in pH can result in them not functioning properly. To maintain these constant pH levels, buffer solutions are used. A buffer solution can resist change to small additions of acids or base’s. A good buffer will have components that act like a base, and components that act like an acid.

For this experiment, titrations on a weak acid, acetic acid, and a buffer were performed. Acetic acid was titrated with NaOH in order to observe the half-equivalence point as well as the equivalence point. Then, the buffer and the buffered acetic acid solution prepared faced additional titration with NaOH and HCl to evaluate the differing buffering effects following the addition of a strong acid and strong base. Finally, the buffer’s buffering capacity was calculated. If the experiment were to be repeated, it would be interesting to observe the buffering effects following a titration between a weak base and a buffer instead with greater concentrations. The change in the concentration following the preparation of buffer with a weak base and its conjugate acid would pose for an interesting experiment to observe an increase in the buffering capacity.

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

If an acid-base disturbance shifts the pH outside of the physiologic range, various control measures are activated to resist the change in pH. Compensatory mechanisms try to preserve the normal 20:1 ratio of bicarbonate to carbonic acid to keep the pH at normal range. The body works to maintain normal ratios through a compensation mechanism using renal and respiratory methods (Crowley, 2010).