When you notice these changes. Then use it to collect about 75 mL of the 0.2 M \(\ce{NaOH}\) solution (available in the reagent fume hood). Answer each question to the best ofyour ability Show ALL calculations and use complete sentences One-word answers will never be given credit Last week in lab, you made : mixture of P-nitrophenolphosphate and enzyme at fixed concentrations Then, you measured the absorbance of p-= -nitrophenol = over time Generate graph that shows how average absorbance changed over time for your reaction best . Explain your answer: pH of Buffer Assigned by Instructor: ______________, Measured pH of Assigned Buffer: _______________ Instructors Initials: _________. At the midpoint of the titration of a weak acid 15. I hope that we get to do another LAB similar to this one later in the year. Do not use any soap as the residue may affect your pH measurements. Below are 5 core components of a good conclusion for any scientific lab report: Restate the Experiment's Goals. It should be between 5.2 and 7.0. Carefully, added 1 drop of hydrochloric acid into the solution of distilled water until the pH dropped 1. The acid reacts with a base to produce water and salt. . A 3 on the pH scale is 100 times more acidic than a 1. If it is found that a substances pH is equal to 7, then its determined to have a neutral pH. Essentially, it follows the scientific method . Data and Conclusions: The purpose of this experiment was to learn how to use distillation and gas chromatography to separate and identify different compounds from a given mixture. . Titrate the solution in the beaker labeled A- until it reaches the phenolphthalein end Select one of the 150-mL beakers and label it NaOH. . Pale Pink Sprite Color with Extract Vinegar Cloudy Pastel Green No Change Dish Detergent Baking Soda Lime Green Ammonia Orange Juice Stayed the same but cloudy Slightly Lighter Brown Coke Table 3: Consists of the color results after the color extract were added to the solutions. where the solution is mixing smoothly but gently. Record this Do not LAB 4: INTRODUCTION TO PH AND PH SCALE LAB 3 the characteristics between acids and bases and this is performed before any values are put through a logarithmic function. Water 6. Fill the buret with the 0-M NaOH solution from your beaker to just above the 0-mL This is, the system that is going to be used in both the micro and macro experiments. Words: 284 . Eventually as \([\ce{H3O^{+}}]\) decreases still further we will have, \([\ce{H3O^{+}}] << K_{ai}\), and the color of the solution will have turned to blue. Solutions that have a high pH level or above 7 are considered basic. The lab manual may dictate where it should appear. Here we are assuming Equation (9) proceeds essentially to completion. At some point during your titration the pH difference between subsequent 0.5-mL additions will start to grow larger. Your graph should have an appropriate title and labeled axes with an appropriate scale. For You For Only $13.90/page! Initially starting at a pH of . Do you know why? Now measure out 25-mL of the solution from the beaker labeled A and combine this value in your data table alongside the measured volume. On one beaker, measure the distilled water with the pH meter and record the pH level. These data will be used to plot a titration curve for your unknown acid. Use your pH meter to determine the pH of each of these four solutions. begins to persist in solution longer before vanishing. When you feel you are Using your pH meter measure the pH of the deionized water. From these two tests we know that the pH is suggested you use only a portion of each of these two solutions in case your first attempt A 3 on the pH scale is 100 times more acidic than a 1. . It is a measure of how many excess H+ ions there are in a solution. Wet lab geneticist turned bioinformatic software engineer. This will ensure \([\ce{A^{-}}]\) in the titrated solution is equal to \([\ce{HA}]\) in the \(\ce{HA}\) solution. containing the remaining 0-M NaOH solution for the next part of this experiment. The actual colors in solution vary somewhat from those shown here depending on the concentration. - Genaro. Table 1 to determine the pH range of four solutions to within one pH unit. Experiment Conclusion, Lab Report Example . ANALYSIS AND CONCLUSION: Analysis: - The pH, or potential of hydrogen, of a substance can be measured by using pH indicators such as litmus paper, . A buret stand should be available in the If time allows you will measure the pH as a function of the volume of \(\ce{NaOH}\) solution added in the titration. After testing all the beakers with the pH meter, add 2 drops of cabbage extract (intoxication) to each beaker and mix it well until there is a distinct color. set aside and the other part will be titrated with NaOH. this beaker, 50-50 buffer mixture.. the buret to the buret stand making sure that it is vertical. In the field of chemistry, pH, which stands for potential of hydrogen, is, perceived as the determination of the acidity or alkalinity of a substance (, determined through a system known as the pH scale which quantifies the potential of acids and, bases based on a scale ranging from 0-14 (, . demonstrate how to use the pH meter appropriately at the beginning of your laboratory session. Measure the pH of each of these solutions following this addition and determine the change in pH of each. Get 5 small beakers and label them A through E. Half fill the small beakers with the appropriate solution as it was done with the prior experiment but this time a pH meter and a cabbage extract called intoxication will be used. When the pink color from the phenolphthalein indicator persists for at least 2 minutes you have reached the endpoint of your titration. If you are being asked to make a buffer at pH 4.00, what is the appropriate ratio of A. 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. You may assume that this Note: There are two procedures listed for this part. As you can see from Equation \ref{1}, the protonated form of the acid-base indicator, \(\ce{HIn}\) (aq), will be one color (yellow in this example) and the deprotonated form, \(\ce{In^{-}}\) (aq), will be another color (blue in this example). Lab Report. Here we are assuming Equation \ref{9} proceeds essentially to completion. You will then combine Proceeding in a similar manner, you will use the acid-base indicators in The easiest part was checking the pH of the substances. pH and color transition The end point is near when the pink color from the phenolphthalein indicator One part you will Record the color of the indicator in each solution on your data sheet. Explain your answer. To each of these test tubes add about 1 mL of 0.1 M \(\ce{HCl}\) (. weak acids where the color of the aqueous acid is different than the color of the corresponding Accurately recording the ion concentration, values for this lab procedure are extremely crucial in order to gain a better understanding. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Rinse your buret, small funnel, and four 150-mL beakers several times using deionized water. The pH scale starts from 0 to 14. 2. All plants received the same amount of sun exposure in the laboratory. Using indicator dyes. Generally only one or two drops of indicator are added to the solution of interest and therefore the amount of \(\ce{H3O^{+}}\) due to the indicator itself can be considered negligible. Recall that the pH of a Summary. . ____________, Which ion, \(\ce{Zn^{2+}}\) or \(\ce{SO4^{2-}}\), is causing the observed acidity or basicity? In this part of the experiment you will use five indicators to determine the pH of four solutions to within one pH unit. GLOVES: Gloves are needed when handling: Introduction: . Rinse two small 100 or 150-mL beakers as before. **Consult your instructor before starting Part D, to see if he/she wants you to follow the normal or OPTIONAL procedure. The coleus in distilled water grew an . One part you will set aside and the other part will be titrated with \(\ce{NaOH}\). 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. Consider your results for the 0.1 M \(\ce{ZnSO4}\) solution. Recall that the pH of a buffer solution is given by the Henderson-Hasselbach approximation: \[pH=pKa+ \dfrac{\log[A^{-}]}{[HA]} \label{10}\]. Note: There are two procedures listed for this part. Course Hero is not sponsored or endorsed by any college or university. State Whether Your Experiment Succeeded. You only need to complete this table if your instructor chooses the OPTIONAL procedure for Part D. This page titled 5: pH Measurement and Its Applications (Experiment) is shared under a CC BY-NC license and was authored, remixed, and/or curated by Santa Monica College. of the buret. . The pH of the solution in your beaker labeled, 50-50 buffer mixture, is also the p K a of Results Solution Color WI Promptly blue Color with Phenolphthalein 6 Cloudy White 9 Blue Pink c 5 Yellow 2 11 Slightly Darker Blue Dark Magenta Table 1: Consists of pH levels of each solutions, the result when added indicator dye Promptly blue into solutions, and the result when added indicator dye Phenolphthalein into solutions. Finally, you will compare the buffering capacity of the buffer you prepare with that of deionized Take on strip of pink and purple litmus paper and submerge the tip of each paper with the substance. As \([\ce{H3O^{+}}]\) decreases the equilibrium indicated by Equation \ref{1} will shift to the right and \([\ce{HIn}]\) will decrease while \([\ce{In^{}}]\) increases. Write the net ionic equation below that shows why this ion is acidic or basic: Consider your results for the 0-M NaHSO 4 solution. Measured pH. solution and that containing the deionized water. If time allows you will measure the pH as a function of the volume of NaOH solution added in The pH scale runs from 0 to 14, with 0 representing the highest concentration of hydrogen ions. your unknown acid. As an example consider an acidic solution containing the indicator \(\ce{HIn}\) where \([\ce{H3O^{+}}] >> K_{ai}\), and therefore, \([\ce{HIn}] >> [\ce{In^{}}]\). 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. For example, Note this point on your data sheet and stop the titration. 0 unit. Youth Agency Marketplace YOMA Training for Young TECH LEADERS Powered by UNICEF Generation Unlimited System Strategy and Policy Lab in collaboration with Initial pH is the result of the reading from pH meter for both solutions and the final pH is the result from adding hydrochloric acid until pH drops 1. value of p K a for the unknown acid. Good Essays. Proceeding in this way, continue to add 0.2 M \(\ce{NaOH}\) to your solution in approximately 0.5-mL steps. additional 0-M NaOH from your beaker and try again. Use the value of the pH at the midpoint of your graph to determine the value of \(K_{a}\) for your unknown acid. 26 Light Pink 2. The five indicators you will use in this experiment, their color transitions, and their respective This can be justified by noting that for the reaction, \(K_{c} = \frac{1}{K_{b}}\) where \(K_{b}\) relates to the reaction of the conjugate base \(\ce{A^{-}}\) with water. You will confirm the pH of this solution using your pH meter. you overshoot the endpoint by more than this you may need to repeat this titration, see Acid-base indicators are themselves 1. Upon completion of the titration, the assign you the pH value of the buffer solution you will prepare in this part of the experiment. Save the remaining solutions in the beakers labeled, HA and A and the beaker Include and Analyze Final Data. methyl yellow First, a lab report is an orderly method of reporting the purpose, procedure, data, and outcome of an experiment. I'm a waste water treatment professional as I gained experience in waste water treatment industry working as a Lab Assistant under R & D department at BPC/NEPL Site, Ahmedabad. Around this time, the pink color from the phenolphthalein indicator will also begin to persist in solution longer before vanishing. Its important to maintain an understanding that when . 5, and the acid has a pH >5. , then an Alizarine yellow indicator may be used. +NH3CH (R)COOH + OH- +NH3CH (R)COO- + H2O. How To Write A Lab Report | Step-by-Step Guide & Examples. slow down your addition rate to just 2 to 3 drops per addition. order now. Example of a Lab Report Conclusion. Using solution into the first beaker and 30 mL of 0-M acetic acid solution into the second. Use your pH meter to confirm the pH of your buffer solution. Balanced Equation: HCl ( aq) + NaOH ( aq) ---> NaCl ( aq ) + H 2 O ( l ) If a reaction happens in your experiment, you must include a balanced equation somewhere in your report. Alkalinity, or "acid neutralizing capacity," is measured by adding acid to the sample and figuring out the equivalent alkalinity in the water. Set the probe off to one side of the beaker so that liquid from the buret can directly enter the beaker during the titration. Part D. Determining the Value of Ka for an Unknown Acid by Titration (Normal procedure). When you are assigned a biology lab report, it is important to understand the purpose of the assignment and how to write a lab report that will be accepted by your instructor. First you will learn aboutthe general operating techniques used with a pH meter and calibrate the meter at pH 10. You will then use this curve to find the midpoint of the titration. Materials and Methods Ph Paper. a colorless solution. directly enter the beaker during the titration. Use Reading the buret carefully, record the exact volume added on your data sheet. The report is intended to complement your bench training by giving you the opportunity to demonstrate your understanding of the biologic significanceof your work as well as The mixture were stirred by using a glass rod until the mixture is fully dissolved. PH Lab Report. Use the known value of \(K_{a}\) for acetic acid from your textbook to determine the percentage error in your measured \(K_{a}\) value for each solution. Report the p K a value you determined for your unknown acid in Part D to your instructor who will You will need to tell your instructor this value for This as the equivalence point of the titration? Select one of the 150-mL beakers and label it NaOH. 871 Words. The Influence of pH on the Activity of Catalase Enzyme Pages: 5 (1203 words) Enzyme catalysis lab Pages: 4 (1078 words) Projectile Motion Lab Report: Lab Assignment 1 Pages: 3 (762 words) Macromolecules lab bio 1 lab Pages: 2 (520 words) Why Lab Procedures and Practice Must Be Communicated in a Lab? Ph Measurement Lab Report. Place 2 drops of color extract (intoxication) in each beaker and make sure it mixes in well until there is a distinctive color. Trial 3: 15.84 mL NaOH. Pages: 12 (3486 words) Into each of your four clean beakers collect about 30 mL of one of the following: Use your pH meter to determine the pH of each of these four solutions. PH of household products. Insert your funnel into the top of the buret. Legal. 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 As [H 3 O+] decreases the equilibrium The solution were tested by using calibrated pH meter to get the pH value of the solution. Is the solution acidic or basic? Rinse and fill another 150-mL beaker with a volume of deionized water equal to that of your and similar size coleus cuttings grew in acidic vinegar water solutions ranging from 2 to 4 pH. Acidic substances have a pH below 7, while alkaline substances (bases) have a pH above 7. The total amount of mixed to form the 50-50 buffer solution? Measure the pH of each of these solutions 2.It is important to stir the solution as u progress through an experiment because it helps make sure that the reaction is complete. You will divide the solution containing this unknown acid into two equal parts. It can detect also weak bases, but mostly, strong. 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You will use these values to calculate \(K_{a}\). **Consult your instructor before starting Part D, to see if he/she wants you to follow the normal Swirl gently to mix. Next, by add a drop of hydrochloric acid and gently swirling the beaker until the pH meter dropped 1. Consider your results for the 0-M Na 2 CO 3 solution. You will need the following additional items for this experiment: pH meter Soapy Water 8 Conclusion In concluding this lab I found that, in general most groups had similar recordings in their lab. Record these values on your From these two tests we know that the pH range our solution is between 2 and 3. WASTE DISPOSAL: All chemicals used must go in the proper waste container for disposal. Now we will test the buffer solution you prepared against changes in pH. Students looking for free, top-notch essay and term paper samples on various topics. congo red (OPTIONAL) Use Excel to create a graph or titration curve of pH versus volume of 0-M NaOH Soapy Water 8 Conclusion In concluding this lab I found that, in general most groups had similar recordings in their lab. The pKa for the buffer is therefore 5.05. Consider your results for the 0.1 M \(\ce{Na2CO3}\) solution. By the pH reading that the pH meter provided, determine which solution from beakers A through E is a base or acid. Although, when testing the pH of soda the recording of pH between groups ranged from 1 to 3. It should be between 5 and 7. 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. Conclusion . 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