PART I. INTRODUCTION The molarity of an unknown acid will be determined using a method called "titration". Titration is the process of the gradual addition of a solution of known concentration to a second solution until the solute in the second solution has completely reacted. A solution of known concentration used in a titration is called a standard solution. In today's experiment, NaOH, a base, is the standard solution. Sodium hydroxide will be added to an unknown acid. The unknown acid and the base reacts and forms salt and water. This type of reaction is called neutralization: NaOH + HA ---> H2O + NaA HA is an abbreviation for an unknown acid. A substance called an indicator is added to show the end of the titration. Attach a buret clamp (located under the hood) to a ring stand. b. Rinse the burets three times with approximately 10 ml of deionized water. Tilt and rotate the buret in an almost horizontal position (don't let the water spillout!) to rinse the entire inside wall. Allow about 5 ml of water to run through the buret tip on the last rinse. c. Pre-rinse one buret with approximately 5 ml of your Unknown acid solution. Again, rotate the buret to rinse the entire inside wall of the buret as above. d. Clamp the buret in one side of the buret clamp. Place a white piece of paper labeled "Unknown acid" under this buret. Drain any remaining pre-rinse acid solution into a beaker labeled "waste solution". e. Fill this buret with your Unknown acid solution to the zero mark or slightly below it (Not above the zero mark). Make sure the tip of the buret is completely filled and contains no air bubbles. f. Pre-rinse the second buret with approximately 5 ml of standard base solution. Clamp the buret in the other side of the buret clamp. Place a white piece of paper labeled "Standard NaOH solution" under the buret. Drain remaining prerinse NaOH solution into the waste solution beaker. Fill this buret with standard Read the initial buret readings for both burets to the nearest 0.01 ml. Use a buret reading card to make the meniscus more prominent. Record readings on the report sheet. Have your instructor check and initial your report sheet for your first buret reading (sample #1, only). 6. Rinse a clean 125 ml Erlenmeyer flask with deionized water. Deliver approximately 20 ml of unknown acid into the Erlenmeyer flask. The tip of the buret should be approximately 1/2 inch below the top of the flask to avoid loss due to splashing. 7. Add 2 or 3 drop of phenolphthalein indicator. (Above your lab bench). 8. Titrate the unknown acid by adding standard NaOH (from the buret). Swirl the flask to mix the solutions during the addition of base. As the base is added you will observe a pink color localized at the spot the NaOH enters the solution (this is due to a localized high base concentration). Occasionally, rinse down the walls of your flask with deionized water (This rinses down any acid that has splashed onto the walls of your flask). Near the end-point, the pink color "flashes" throughout the solution and remains for a slightly longer time (1-2 seconds). When this occurs, add the NaOH drop by drop and eventually half-drops until the pink color remains (for at least 30 seconds). This is the end-point! NOTE: If you over-shoot the end-point (too much NaOH is added), add 1-2 more ml of the Unknown acid and then add NaOH again until a proper end-point is reached. Be sure
According to the graph on amylase activity at various enzyme concentration (graph 1), the increase of enzyme dilution results in a slower decrease of amylose percentage. Looking at the graph, the amylose percentage decreases at a fast rate with the undiluted enzyme. However, the enzyme dilution with a concentration of 1:3 decreased at a slow rate over time. Additionally, the higher the enzyme dilution, the higher the amylose percentage. For example, in the graph it can be seen that the enzyme dilution with a 1:9 concentration increased over time. However, there is a drastic increase after four minutes, but this is most likely a result of the error that was encountered during the experiment. The undiluted enzyme and the enzyme dilution had a low amylose percentage because there was high enzyme activity. Also, there was an increase in amylose percentage with the enzyme dilution with a 1: 9 concentrations because there was low enzyme activity.
The equation shows how 1 mol of Na2CO3 reacts with 1 mol of H2SO4, so
Then, the weak acid was isolated from the NaOH extract. After cooling the mixture, HCl was pipetted into the flask, neutralizing the NaOH. This enabled the, now precipitated, weak acid to be filtered out of the solution. After vacuum filtration was used to remove the solid acid, percent recovery was recorded, and the weak acid was moved to a
I am not going to carry out the experiment with 0 molar acid, as this
Investigation 20 used spectroscopy along with stoichiometry to determine how much of cobalt was present in a soil sample. The real world application of spectroscopy is endless but one particular scene where spectroscopy is crucial is its application to law enforcement and forensic investigation. While the type of spectroscopy used is different than that used in the laboratory investigation the same basic principles apply. Spectroscopy in its different forms is used to catch the degenerates and is one science that works to make society a better place.
The concentration of the unknown HCl solution was found to be .102 M, and the concentration of the unknown acetic acid was found to be .053 M. As shown in Graph 2, the equivalence point volume can be shown by the maximum slope, and this volume was found to be 25.49 mL; the equivalence point volume of acetic acid was found to be 13.89 mL. The equivalence point volume was found by using the first derivative plot and looking at the highest slope. Phenolphthalein would be a good indicator for giving a reliable determination of the equivalence point. In the forward reaction of the HCl + NaOH and acetic acid + NaOH, the phenolphthalein clearly changed color from fairly clear to a pinkish color once the solution started becoming more basic. If an unknown weak ammonia solution was titrated with the strong acid HCl, then the phenolphthalein would not be an ideal indicator to use because the color change for the reaction between the weak ammonia (weak base) and HCl (strong acid) should occur at the likely equivalence point between 4 and 6; phenolphthalein changes color at the pH range of 8-10, so it would not be ideal use phenolphthalein because it does not have a color change at a pH range near the equivalence point pH of the weak base (ammonia) and strong acid (HCl).
The procedure of this lab experiment has five different steps. The first step in this process is to gather the materials which are cups, shells, acid, measuring spoons, and an electronic balance. The next step in the procedure is to put the acid in three different cups cup A one whole cup, cup B one fourth of a cup, cup C one half tbs. The third step is to put 120
As 10 mL of NaOH was added drop wise, the solution began to have a pink tint. The fuchsia color did not permanently stay until 9mL of NaOH was added. The pH indicator demonstrated when exactly the reaction has neutralized. Because an acid and a base reacted to form water and a salt, the reaction is a neutralization
tube. Add 6 mL of 0.1M HCl to the first test tube, then 0.1M KMnO4 and
Titration Practical Planning assessment The apparatus to be used: · Beaker · 250cm 3 volumetric flask · Funnel · Burette · Pipette · White tile · Conical Flask · Balance · Spatula · Weighing bottle · Glass rod Method Making a standard solution: A weighing bottle was accurately weighed and approximately 5g of anhydrous sodium carbonate was added and the weight of the bottle plus the solid recorded. The anhydrous sodium carbonate was then transferred into a 100cm3 clean beaker. The bottle was carefully rinsed out two or three times with water and the washings were transferred to the beaker each time. About 25cm3 of water was poured into the beaker and stirred with a glass rod until the solid had completely dissolved.
Take 0.1g of mustard oil in a conical flask and add 25 ml of 0.5M alcoholic KOH to it. Boil the mixture on water bath until the clear solution appears. Cool the mixture and add 2-3 drops of phenolphthalein indicator. Then titrate it with 0.5N HCL solution. Conducts the blank titration along with the sample add all the reagents except the sample.
A titration method is conducted by the addition of a standard solution from a burette until reaction is completed. The volume of reagent needed for the completion of titration can be determine from the difference between the initial and final volume readings. When an analyte reacts with a reagent of known concentration, it is called as titration. Analyte is a chemical substance that is a chemical analysis subject 1. Titrant is the standard solution added from the burette. The volume of required titrant to react completely with analyte is measured as the volume of equivalence point. Titration are usually classified based on the reactions that take place and the technique applied to detect the equivalence point. For titration to be successful,
Titration is a technological process in which a solution, known as a titrant, is slowly and carefully added from a burrette into a fixed volume of another solution (known as the sample). In an acid-base titration an acid neutralizes a base or vice versa. This process is maintained untill the reaction between the titrant and the sample (acid and the base) is judged to be complete. The reaction is judged to be complete when the endpoint is reached. An endpoint in a titration analysis is referred to as the point at which no more titrant is added due to an observable colour change of an indicator. Indicators can be used to find an endpoint because they change colour when the pH of a solution changes and an endpoint in a titration is an empirical approximation of the equivalence point, which is the point of major pH change in the titration sample due to the fact that equal chemical amounts of reactants have been combined at that point. All indicators have a pH range, which is the range of pH values at which the colour of the indicator changes. Thus
In this experiment we are trying to identify an unknown acid or base and its concentration by using the method of titration. The pKa values and the titration curve help aid in identifying of the unknown. In our case we had a base as our unknown (analyte). The use of a certain amount of sodium hydroxide and hydrochloric acid will be used to titrate the unknown solution that is given. This is the tirant. We used hydrochloric acid as our titrant. We achieved a pH of 5.56 at an end point of 10 milliliters. The unknown’s concentration was around 0.098 M at pka(s) of 6 and 7. The sodium hydroxide and hydrochloric acid are called titrant and it is contained in a container called burette. The unknown solution is held in an erlenmeyer flask. The purpose of the experiment is to measure the weak acid and base by neutrilizing it and determining the unknown acid by titration.
In this experiment three different equations were used and they are the Stoichiometry of Titration Reaction, Converting mL to L, and Calculating the Molarity of NaOH and HCl (Lab Guide pg. 142 and 143).