Chemistry Titration Acid Base Lab Essay

Question What effect does an index fingers pH cast thrust on the exterminate point of the titration of vinegar and 1.00 mol dm-3 of atomic number 11 hydrated oxide ascendent?Equation CH3COOH (aq) + NaOH (aq) NaCH3COO (aq) + HOH (l)Data Collection board A Table Representing the initial Volume of NaOH in the buret, the Final Volume of NaOH in the Burette and the Difference amongst Those Values for Specific Trials When Using Different exp matchlessnts. in that location were a minimum of three runnings per body-builded for this laboratory as on that point indispensable to be three of the same rest between the final and sign burette readings of the atomic number 11 hydrated oxide. This is delinquent to the fact that a titration lab requires genius to acquire three of the same shelters for this section to understand the lease get of topic required to put on the term of the chemical fight backion.IndicatorInitial Volume of NaOH resultant role (ml) 0.05Final V olume of NaOH dissolving agent (ml) 0.05Difference in the midst of the Final and Initial Burette Readings (Volume of NaOH exercising upd) (ml) 0.1Qualitative Observations1. Calculate the Initial constriction of acetic Acid Before Diluted With Distilled WaterC1V1 = C2V2C1= C2V2V1C1= (0.09mol/dm3)(0.1L)(0.01L)Concentration of Acetic Acid Before Dilution = 0.9mol/dm3Sample Calculation B Calculating percent Uncertainty for the Volume of sodium Hydroxide Needed for Different Indicators role model Bromocresol Green==25.0%Sample Calculation C Calculating the Percent errorPercent error ) cytosine) 100=0.034%Sample Calculation D Propagating Uncertainty for the Volume of Sodium Hydroxide live with for Each Indicator= (0.90.1) + (1.50.1) + (0.20.1) + (2.90.1) + (0.40.1)= 5.9ml0.1Graph A Titration rick of the Amount of Sodium Hydroxide Required to R separately the shuttingpoint for Different Indicators TestedGraph B Titrations curve of a strengthened plinth and sapless dit. Approx imately 9.2 is the pH of the comparing point as seen in the graph.ConclusionThis lab required one to determine the different muckles of sodium hydrated oxide base required to reach the end point of a titration with acetic virulent as the analyte when employ different indicators. The equation is as followedCH3COOH (aq) + NaOH (aq) NaCH3COO (aq) + HOH (l)It was determined that phenolphthalein was the opera hat indicator for exercising in this lab. This is due to the fact that the vinegar that was utilize in expression division has an acetic sultry slow-wittedness of 0.87 mol/L which is 5.0% acetic pane of glass (Meheen, n.a). In the lab, phenolphthalein required 0.90 mol/L of the sodium hydrated oxide firmness of purpose in target for a warp trans cause to undertake endow (endpoint was reached). This value is fairly close the concentration of acetic corrosive in the vinegar utilise in the lab, then, phenolphthalein was the most accurate of indicators utilized in this titration lab.Through research it has been determined that phenolphthalein should contain, in fact, been the best indicator of use. Phenolphthalein has a pH cut back between 8.0 to 9.8 which is an bewitch range for a weak acid strong base titration. This is because the par point for this titration exclusivelyow take nonplus at a point of pH approximate to 9 which f totallys into the pH range for the indicator phenolphthalein. This can buoy be seen in Graph B. This equivalence point leave behind be greater than 8.7 as the weak acid (vinegar) only partially dissociates and releases a little amount of its hydrogen ions, making it a weak acid. On the other hand, sodium hydrated oxide contains sodium acetate which raises the pH considerably of the vinegar as it is fairly prefatorial. Therefore, the equivalence point leave be greater than heptad and more(prenominal) specifically approximate to 9. All of the indicators that were used did non birth a pH range above 9 except for phenolphthalein. This is the moderateness why phenolphthalein was the best indicator.Graph A illustrates the different volumes of sodium hydroxide that was selected to reach the endpoint of the reaction when universe added to a solution of vinegar utilize various indicators. The least amount of sodium hydroxide required to reach the endpoint of the reaction for the indicators used are displayed as followed methyl orange, bromocresol green, phenolphthalein, bromothymol blue and methyl red. Many indicators were used to determine which one was right for this specific lab. It was requirement to determine which indicator was correct for this lab. This can be explained by the equivalence and endpoint. The equivalence point is the point of the reaction when one has added the correct amount of the base to the acid. However, the endpoint is the point in which the indicator flips color. Error bars are not present on the graphs displayed as titration labs require one to do co ntinue experimentation for a test using a specific indicator until they have leted a value for the deviance between the final and initial burette readings (volume of NaOH used) a minimum of three times.The vinegar had a pH or almost 2.4 making it highly acidic (Rousseau, 2012). Therefore, the equilibrium will be on the left. However, when the sodium hydroxide basic solution was added to the vinegar, the equilibrium started to shift more to the right. For instance, when base was being added to the vinegar solution with the indicator Bromocresol green, the color of the solution false from yellow to green. When the green color is seen, the end point has been reached however, if the color becomes blue then over-titration has taken coif, indeed shifting equilibrium unconstipated further to the right.There were few anomalous results that arose during the course of the lab. For instance, for the test using phenolphthalein, one trial had a considerably larger difference between the final and initial burette readings (volume of NaOH used) of 1.4ml. The other trials all had a difference of 0.9ml for using this specific indicator. This can be seen in all tests using different indicators except one represented in data array table A, Bromocresol green. This proves that there were systematic and/or random errors that took menage during the lab. paygradeThere were few errors that took locate during the course of experimentation. These errors could have negligibly affect the results obtained end-to-end the process. One considerable error that took place was making the sodium hydroxide solution. 1gram of white crystalline sodium hydroxide pellets were required in order to create the solution. Unfortunately, while the pellets were being measured on the electronic residuum they interacted with moisture from the air. Additionally, the pellets were put in the volumetric flaskful when irrigate that would laterwards mix with these pellets was being measured in the g raduated cylinder. Therefore, there was bulk of time before the water was placed in the volumetric flask for the sodium hydroxide pellets to absorb moisture from the air. This is a concern as consentient sodium hydroxide has the formula NaOH (s). Additionally in air there is carbon dioxide (CO2). The formula for the reaction between this carbon dioxide and the solid sodium hydroxide is as follows2 NaOH + CO2 Na2CO3 + H2OTherefore, the hydroxide from the sodium hydroxide and the oxygen from carbon dioxide combine to from water (H2O) which affects the results that were obtained in the lab (ATSDR, 2011). This is because the sodium hydroxide concentration in the solution that was do to act as the base, would have decreased as the pellets reacted with air to form water. It would have been beneficial to purchase the specific amount (in grams) of sodium hydroxide pellets that was necessary for this experiment (1gram). This would check off the sodium hydroxide pellets would not react w ith the carbon dioxide in air for in truth long before being put in the volumetric flask with water added. This is because there would be no need to measure these pellets on the electronic balance.A very common error with titration labs is that over-titration often occurs. This is the point in which too oft titrant is added to the analyte during a trial. Therefore, the reaction passed the endpoint as too ofttimes of the basic sodium hydroxide was added to the acidic vinegar solution containing acetic acid. Unfortunately, this took place for most trials. For instance, phenolphthalein reaches its endpoint when it mixtures from being clear and transparent to becoming a light shade of pink.Though this may be, for all of our trials when using this indicator the color became a hot pink shade proving that over-titration had taken place. An service for this component of the lab is simple. An improvement to control this error would be to use a burette with a smaller unmannerlying. This is because the endpoint can be overshot quite easily and this would turn back the error would not take place. It would have been best to manage the amount of base entering the beaker as much as possible with greater accuracy.An additional error that took place was how the stopcock was not entirely effective. This is due to the fact that when the stopcock was turned to close the burette aerofoiling, little droplets of sodium hydroxide would still teem into the beaker. This means that if the solution had reached the endpoint and additional droplets were leaked from the beaker an inaccurate reading of the sodium hydroxide in the burette would be recorded. This error could have been alter by using a BT50 digital burette (Bibby, 2010). This burette would ensure that a considerably small amount of sodium hydroxide would be discharged from the turn at most. A button will be pressed to stop the base from entering the beaker containing the acid electronically. The accuracy of this inst rumentate is within 0.2%, and precision is better than 0.1% allowing for the most accurate of results to be obtained.Temperature should have been controlled through by the process as it does play a role in affecting the data obtained in a titration lab. The volumetric glassware used for the purpose of this lab is calibrated at 20oC and a higher temperature of a solution would result in it holding a greater volume than desired (Atkins). Since the inhabit temperature is approximately 24oC it can be assumed that the temperature of the solutions used in the experiment were greater than 20oC. Therefore, these solutions can expand and the concentration in molarity would decrease.Therefore it would have been beneficial to keep the temperature of the acid and base constant at 20oC. This could have been achieved by using an alcohol thermo molarity. If the temperature for the acid and base were not 20oC, than it would either need to be placed in the refrigerator if the solution was too hot o r would need to be put in a beaker and on a hot shield to reach the desired temperature.The temperature for each indicator that was used was not concordant throughout the lab. This is because the temperature of the room changed throughout experimentation. The door in the classroom was open to get rid of the stench from a lab done in the previous class. Therefore, the temperature of the classroom was gradually getting colder and colder. A consistent temperature for each indicator would ensure that the pH range for a color change would not increase or decrease. This is because with a decrease in temperature there is less ionization that takes place allowing the pKa value to increase and therefore, the color change will occur at a higher pH.To ensure all the temperatures of the indicators were kept consistent throughout the lab it would have been beneficial to use an alcohol thermometer and place it in the indicator solution before conducting the trial (ChemBuddy, 2009). If the tempe rature changed for one trial, the indicator would either need to be placed in the refrigerator if the solution was too hot or would need to be put in a beaker and on a hot scale to reach the desired temperature. The table below represents how temperature can affect the pH range for a color change for specific indicators. To ensure this does not occur, the lab should be taken out in a room with no windows so the temperature does not change. The table below represents how the endpoint changes with a change in the temperature of an indicator.IndicatorColor Change Range18oC100CMethyl Orange3.1-4.42.5-3.7Methyl Red4.4-6.24.0-6.0Phenolphthalein8.2-9.88.1-9.0Quoted from Chemia analityczna, J.Minczewski Z.Marczenko, PWN, Warszawa 1973.another(prenominal) error was that there were bubbles in the burette tube. When the sodium hydroxide solution was pour outed in the burette it was done quite quickly creating many bubbles in the beaker. Unfortunately, my group could not afford rinsing the so lution out and gushing(a) in more sodium hydroxide solution because we wanted to ensure we had enough of the solution for the whole lab. Therefore the bubbles caused an inaccurate volume reading. The bubbles disport a particular amount of volume and this means that the volume in the burette would in fact be less than the amount account during trials. Since the bubbles all formed near the stopcock it would have been best to pour the sodium hydroxide solution into a waste beaker in hopes that the bubbles would be eliminated before beginning the trial.This is because the pressure of the titrant in a burette will force the bubbles out. Unfortunately, in about cases the bubbles remain near the stopcock. If this is the case, it would be best to use a suction method approach. This involves one to partially open the stopcock allowing the contents of the burette to discharge in the beaker. Then, they will use the pipet bulb to suck air from the bubbles through the nozzle of the burette. This will drive out the air bubbles present in the solution out of the beaker into the suction device. One must ensure that the sodium hydroxide that was poured in the beaker during this process is accounted for by slowing pouring in the amount necessary in the burette for the trial to begin.One experimental error that was needful was the cleaning of the burette before using it. It was necessary to clean the burette using water, as it may have had some residue or contamination from a previous experiment. Additionally this residue could have affected the pH of the sodium hydroxide solution that was to be put in the beaker for the purpose of this titration lab. However, there were some droplets of water left on the sides of the beaker after it was cleansed which would have decreased the concentration of the sodium hydroxide solution that was subsequently poured in this material and lowered the pH level of the sodium hydroxide solution as water is neutral (pH of 7.0). With a lower co ncentration of sodium hydroxide in the base, the pH would have decreased therefore allowing more of this base to be added to the vinegar in order for the endpoint to be reached in a reaction. This is due to the fact that sodium hydroxide is a highly basic solution and water is neutral. When they are heterogeneous the pH of the solution will be lower than the initial pH of the sodium hydroxide solution.An improvement for the lab could have been to detect the pH of the acid base titration once it has reached the endpoint using a pH meter. This was one of the limitations in this acid-base titration lab as the indicators that were used did not translate a change in color at an exact value of pH but only changed in a specific range of the pH. For example, the indicator Bromocresol green changes the color of the solution of a pH range between 3.8 to 5.4. This range is considerably large resulting in one to obtain results that are not necessarily the most accurate. An improvement for thi s component of the lab would have been to use a pH meter. A pH meter is a device that that measures the pH of a solution by find out the voltage of the solution by immersing two electrodes in it. Then, the reading device will present the pH value. This would have led for the most steady-going pH readings to be obtained and the correct amount of sodium hydroxide to be added to the acidic solution.The lab could have been furthered in several ways. It would have been evoke to test these different indicators and the amount of sodium hydroxide required for the end points to be shown when using a strong acid and base. At the equivalence point the same amounts of hydrogen and hydroxide ions will form water, therefore having a pH of 7. For instance, if hydrochloric acid and sodium hydroxide were used the succeeding(a) reaction would take placeHCl(aq) + NaOH(aq) H2O(l) + NaCl(aq)H+(aq) + Cl-(aq) + Na+(aq) + OH-(aq) H2O(l) + Na+(aq) + Cl-(aq)H+(aq) + OH-(aq) H2O(l)The first equation di splays the reaction between the strong acid and strong base. The second reaction displays the HCl and NaOH dissociated in their respective ions. The last equation is cognize as the net ionic equation which eliminates the spectator ions from the previous equation. This proves that water will be produced. The neutralisation reaction will take place because salt will also be formed. This is because the anion from the dissociation of the strong acid and the cation from the dissociation of the strong base will come together to form the salt. The salt is not seen the net ionic equation as it dissociates.For this acid base titration lab it was legitimate to compare the outcomes with other classmates to determine if there were any anomalies between the data that was obtained. This is because it would have provided one with the knowledge of the types of errors that occurred and how much it affected their data. For instance, Sarah and I compared our results with Rachel Hung and Yashna Lakhan is group.Yashna and Rachels groups provided information upon different indicators and some of the ones my group used as well. When comparing with the data of these groups it was determined that all of the results were mostly exactly the same or off by 0.1ml for the difference between the final and initial burette readings. For instance, for phenolphthalein, the value my group obtained for this was 0.9ml however, Yashnas group got 1.0ml. This could have been due to a human error know as a parallax. A difference of 0.1ml could have taken place as one of our groups were unable to determine the position of the meniscus on the burette and therefore, the wrong readings of sodium hydroxide solution could have be collected.An acid base titration has several uses. One of the main real life story uses of this experiment is to mix compounded drugs. A pharmacist will need to mix drugs appropriately in order for them to be in the appropriate pH range for the human body. Antacids are commonly us ed to assist issues concerning heartburn, acid reflux and more. These feelings most likely take place due to excess hydrochloric acid in the last which causes an uncomfortable feeling. This subsequently allows a backflow of this acid to go up the esophagus which can father someone feel like their throat is burning. These tablets counteract the acidity as they go to the stomach area and react with the hydrochloric acid. These tablets are basic and change the liquid in the stomach to being not as highly acidic. Common antacid tablets contain Mg(OH)2 and Al(OH)2. A reaction equation by using an antacid tablet is shown as followedHCl+NaOH NaCl+H2OThe acid base titration in this case is used to determine the amount of the stomach acid present in ones body. Therefore, it can be observed how much antacid will be needed for someone relations with the issues mentioned above in order to make the hydrochloric acid present in their stomach less concentrated (Cavite, 2010). This will ensure the pH of the stomach will be less acidic. In other words, the lab will determine how much hydrochloric acid will be needed to be titrated by the base.Bibliography1. Acid-Base Indicators. Acid-Base Indicators. N.p., n.d. Web. 13 Nov. 2012. .2. Meheen, T. 3- Lab. Titration depth psychology of Vinegar. N.p., n.d. Web. 13 Nov. 2012. .3. Rousseau, Sasha. If You Dilute Vinegar, How Will It pertain the PH Value? EHow. Demand Media, 07 July 2011. Web. 13 Nov. 2012. .4. Toxic Substances Portal Sodium Hydroxide. Sodium Hydroxide (NaOH). N.p., 22 Apr. 2002. Web. 3 Mar. 2011. .5. Downloads. Stuart Digital Burette. N.p., n.d. Web. 13 Nov. 2012. .6. calibration OF VOLUMETRIC GLASSWARE. CALIBRATION OF VOLUMETRIC GLASSWARE. N.p., n.d. Web. 13 Nov. 2012. .7. Acid Base Titration End Point Indicators. Acid Base Titration End Point Indicators. N.p., n.d. Web. 13 Nov. 2012. .8. Pallas_reg. Acid-Base Titrations Analysis of Antacid Tablets. Scribd. N.p., n.d. Web. 13 Nov. 2012. .