Results and Discussions pH ratio between acid and base: 7.3 = 6.82 + x x = 0.48 0.48 = log ([base])/([acid]) 100.48 =base/acid salt/acid = 3.02 There, 1 acid : 3 base beaker. 1. solution to completely dissolve the solid acid. In this experiment it is OK if you overshoot this mark by a few drops. Obtain a vial containing your unknown solid acid from your instructor and record the This relationship will help in determining the acidity or alkalinity (basicity) of the, This lab is going to focus on the behavior of pH as well as the correlated characteristics found, within substances. The main purpose of a lab report is to demonstrate your understanding of the scientific method by performing and evaluating a hands-on lab experiment. I hope that we get to do another LAB similar to this one later in the year. A buret stand should be available in the In this part of the experiment you will prepare a buffer solution with a pH specified by your Is the solution acidic or basic? For example, Conclusion By using the pH paper, dye indicators and the pH meter as tools of measurement, it has helped to determine which is more precise for this study. procedure is appropriate for your lab section. Get 2 sets of test tubes and the label them A through E. Fill the tubes with equal amounts of solution and then in only the first set of tubes, place 2 drops of Promptly Blue dye into each and make sure it mixes in well with the solutions. axes with an appropriate scale. 0 pH unit on the pH meter. The acid reacts with a base to produce water and salt. Save the remaining solutions in the beakers labeled, HA and A and the beaker 4 Pages. This Continue recording the total volume added and the measured pH following Note: There are two procedures listed for this part. Explain your answer. determine the percentage error in your measured K a value for each solution. To conclude, this was a very interesting project. Its important to maintain an understanding that when . The easiest part was checking the pH of the substances. essentially the same as color I. Record these values on your data sheet. This tells us that the pH of our unknown solution is greater than or equal to 2 because methyl violet turns violet at pH values of 2 or greater. Chapter 7 Lab Report Background Research pH is a measure of the potential hydrogen ion concentration of a solution. a colorless solution. the 50-50 buffer solution: (OPTIONAL) Is the endpoint of your pH titration that you marked on your titration curve the same 1. Rinse two small 100 or 150-mL beakers as before. solution in your beaker, low enough down that the meter can read the pH, but high Table 1 to determine the pH range of four solutions to within one pH unit. sodium carbonate Which ion, Na+ or CO 32 is causing the observed acidity or basicity? Finally, you will compare the buffering capacity of the buffer you prepare with that of deionized Now we will test the buffer solution you prepared against changes in pH. Rinse the tip of the pH pen with tap water between tests. Before continuing, the pH meter needs to be calibrated. There was nothing difficult in this experiment. **Consult your instructor before starting Part D, to see if he/she wants you to follow the normal In general we can say that an acid-base indicator changes color at a pH determined by the value of \(K_{ai}\) or pKai for that particular indicator. Step 2: Discuss the Experiment and hypothesis in the lab report conclusion. What is \(K_{a}\) for the acid? ANALYSIS AND CONCLUSION: Analysis: - The pH, or potential of hydrogen, of a substance can be measured by using pH indicators such as litmus paper, . The mixture were stirred by using a glass rod until the mixture is fully dissolved. your unknown acid. Is the solution acidic or basic?____________, Which ion, \(\ce{Na^{+}}\) or \(\ce{CO3^{2-}}\) is causing the observed acidity or basicity?____________, Consider your results for the 0.1 M \(\ce{NaHSO4}\) solution. To measure the pH of various solutions using pH indicators and meter. Words: 284 . Throughout the, macro lab procedure, pH meters are bound to be the necessary tool when trying to measure the, values of pH. Then use it to collect about 75 mL of the 0.2 M \(\ce{NaOH}\) solution. PH paper (litmus paper) determines how acidic or how basic a substance is. Swirl gently to mix. You will divide the solution containing this unknown acid into two equal parts. Clamp You will need to tell your instructor this value for Once calibrated, measure the pH level of beaker A until the meter gives the result of the solution. Table B: pH Data for Acetate Buffers (Indirect Method) 2. Accurately recording the ion concentration, values for this lab procedure are extremely crucial in order to gain a better understanding. Lab Report. Add 5 drops of the remaining 0 M NaOH solution to both the beaker containing your buffer How do you know the concentrations of HA( aq ) and A( aq ) were equal in the two solutions you congo red turns violet at pH values of 3 or less. Introduction. Experiment Conclusion, Lab Report Example . Record the results. this beaker, A. of the solutions listed in part A of the report sheet. Consider your results for the 0.1 M \(\ce{ZnSO4}\) solution. Soapy Water 8 Conclusion In concluding this lab I found that, in general most groups had similar recordings in their lab. 3- Apparatus. An acid-base indicator is a chemical species that changes color at a specific pH as the pH (acidity) of the solution is varied. Note that when [H 3 O+] >> K ai, [HIn] >> [In ] (the equilibrium will be Restate the Experiment's Goals. Data Table: Substance pH Value Acid, Base or Neutral. 26 Light Pink 2. Show your calculations. The final pH's were found and recorded, making it possible to determine that unknown solution 1 was buffered since the pH barely changed from initial to final in both cylinders. Solution X was tested with several acid base indicators and gave the following results: violet in methyl violet, yellow in thymol blue, yellow in methyl yellow, orange red in congo red and green in bromcresol green. amount of the 0-M NaOH you added during your titration and add this volume of Suppose we take intermediate concentrations around 0.1 M. Add very dilute HCl (around 0.01 M HCl) to the water solution. labeled HA and transfer this volume to your fourth clean rinsed 150-mL beaker. GENERAL SAFETY: Students must wear safety goggles and lab coats at all times. What we would probably change next time would be to organize better and write in a more organized way out . When the solution added for your pH titration data. System Strategy and Policy Lab is deeply committed to delivering reforms and results.for the government and non-governmental organizations & institutions | 13 comments on LinkedIn Ph Lab Report. BG 0008-week312010 - lab report; 1142882 - lab report; WH Module 5 - Notes from lecture; Critical Thinking - Prof. Rule; 360 9 - lab report; Preview text. will ensure [A] in the titrated solution is equal to [HA] in the HA solution. shifted to the left in accord with Le Chatelier's principle) and the color of the solution will be Continue to record the volume added and the pH after each addition. Label this second beaker HA and set it Then use these colors and Table 1 to estimate the pH range of each solution (for example, pH =1-2): Record the measured pH and the color of bromcresol green indicator observed for each solution: Complete the following table. It is a measure of how many excess H+ ions there are in a solution. - Genaro. each addition on your data sheet. You will then combine equal volumes of these two solutions in order to form a new solution. The color chart gives you a number on where in the pH level it would land on but could be misread by human error. Using Equations \ref{3} and \ref{4} in the background section of this experiment, show that \(K_{a} = [\ce{H3O^{+}}]\) for the 50-50 buffer solution: (OPTIONAL) Is the endpoint of your pH titration that you marked on your titration curve the same as the equivalence point of the titration? A lab report conveys the aim, methods, results, and conclusions of a scientific experiment. By using the pH paper to measure the solutions A through E it would point out what substance is an acid and which one was basic. The actual colors in solution vary somewhat from those shown here depending on the concentration. Performing this experiment is also, motived by the numerical correlation that the pH of a solution has on certain factors such as ion, concentration. The second pKa is around 8.8. Measured pH. bromcresol green indicator as expected? By measuring the pH levels from the distilled water solution with the pH meter, it gives a numeric reading for water which becomes the initial PH. 15. in Figure 1. Sodium bicarbonate (NaHCO 3) is formed. Values on the pH scale that are greater. Select one of the 150-mL beakers and label it NaOH. Summary. We can represent the dissociation of an acid-base indicator in an aqueous Remove the funnel. In other words the solution will change color when \([\ce{HIn}] [\ce{In^{}}]\), and so \(K_{ai} = [\ce{H3O^{+}}]\), or \(pK_{ai} = pH\). begins to persist in solution longer before vanishing. Adding too much NaOH, to a pH beyond its second pKa results in a colorless solution. 2.It is important to stir the solution as u progress through an experiment because it helps make sure that the reaction is complete. WASTE DISPOSAL: All chemicals used must go in the proper waste container for disposal. Rinse this beaker once more with about 5 mL of 0.2 M \(\ce{NaOH}\). The ones we have in lab are fairly self-explanatory so we would like you to independently figure out how to calibrate the lab pH meters. Do not be alarmed if this pH is less than neutral. I . spam or irrelevant messages, We use cookies to give you the best experience possible. Clean up. Reading the buret carefully, record the exact volume added on your data sheet. At some point during your titration In general we can say that an acid-base indicator Note this point on your data sheet and Which has the lower pH and why is its pH lower? The solution were tested by using calibrated pH meter to get the pH value of the solution. The pH of the solution in your beaker labeled, 50-50 buffer mixture, is also the p K a of stop the titration. Thus we can use the midpoint of the titration curve to confirm the value of pKa for the unknown acid. You will need the following additional items for this experiment: pH meter, magnetic stirrer and stir-bar, 50-mL buret. Extract of sample "PH Determination of Solutions". with water. Then, 20 drops were added and gently swirling the beaker to mix the solution and the hydrochloric acid and wait until the pH meter dropped 1. help. Thus, we have determined the pH of our solution to within one pH unit. 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https://chem.libretexts.org/@app/auth/3/login?returnto=https%3A%2F%2Fchem.libretexts.org%2FAncillary_Materials%2FLaboratory_Experiments%2FWet_Lab_Experiments%2FGeneral_Chemistry_Labs%2FOnline_Chemistry_Lab_Manual%2FChem_12_Experiments%2F05%253A_pH_Measurement_and_Its_Applications_(Experiment), \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}}}\) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\), 4: Determining the Equivalent Mass of an Unknown Acid by Titration (Experiment), 6: Qualitative Analysis of Group I Ions (Experiment), Part C: Using pH to Determine the Value of \(K_{a}\) for Acetic acid, \(\ce{CH3COOH}\)(aq), Part D: Determining the Value of \(K_{a}\) for an Unknown Acid by Titration, Part A: Determination of pH using Acid-Base Indicators, Part C: Using pH to Determine the Value of \(K_{a}\) for Acetic Acid, \(\ce{CH3COOH}\) (aq), Part D: Determining the Value of \(K_{a}\) for an Unknown Acid by Titration (Normal procedure), Part D: Determining the Value of \(K_{a}\) for an Unknown Acid by Titration (OPTIONAL procedure), Lab Report: pH Measurement and its Applications, Part A Determination of pH using Acid-Base Indicators, Part C Using pH to Determine the Value of \(K_{a}\) for Acetic Acid, \(\ce{CH3COOH}\) (aq), Part D Using a pH Titration to Determine the Value of Ka for an Unknown Acid, Pre-Laboratory Assignment: pH Measurement and Its Applications, status page at https://status.libretexts.org. 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