Also you will need to make sure there are no air

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the level drops within the graduations. Also, you will need to make sure there are no air pockets. 5. Standardization: Weigh out approximately 0.025 g of potassium hydrogen phthalate. Into a 125mL Erlenmeyer flask. Dissolve the salt in approximately 50 mL of distilled water. Add 2 or 3 drops of phenolphthalein indicator to the standard contacting the potassium hydrogen phthalate. Record the initial volume of the burette. Add titrant slowly while swirling the standard solution. Erlenmeyer flasks are specifically designed to swirl solutions easily. The goal of the titration is to have a single drop of the titrants cause a permanent change in the color of the standard solution, endpoint is reached at this moment. Record the volume of the burette endpoint, repeat this step two additional times 6. You will be analyzing the process of this titration differently than how you did for the standardization. You will not use an acid base indicator and instead you be using a pH probe to monitor the progress of the analysis. 7. The probes are not used often over the course of the year, so it is important to calibrate them prior to use using a two-step calibration 8. In the process of standardizing you were required to use an Erlenmeyer flask and swirl by hand. For this portion you will be using a magnetic stirrer and a bar to save your hand from cramping. Obtain a larger beaker that will hold a 50mL sample of the diluted acid and keep the pH probe a safe distance away from the stir bar. Use a 50mL volumetric pipet to collect a precise volume of the diluted vinegar. Place the diluted vinegar into the
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Owen Kulp Period: 2 Academic Chemistry 11 Partners: Phoebe Jenkins, Isabella Pizzelanti beaker and place the beaker onto the magnetic stirrer, drop a small magnetic stir bar into the solution, arrange your probe away from the bar and turn the stirrer on. 9. Change the data collection from time based to entry based. Begin data collection and take the first point prior to using any titrant. Record the initial volume of the burette and add less than .5 mL of titrant. Take the measurement and subtract the initial volume from it. Allow the probe to stabilize and then enter the volume and save the point. Continue this process by adding less that .5 mL increments and always subtraction the very first volume measurement. 10. Stop data collection when the pH curve contains the three major sections. 11. Dispose of all waste into the designated ‘Acid-Base waste” container so it can be treated prior to disposal. 12. Clean and return all equipment, return goggles and aprons, and begin working on claculations for your lab report. Data and Calculations Raw Data Trial Initial Volume (mL) Final Volume (mL) Mass of Standard (g) Molarity of titrant (M) 1 46.8 39.9 0.025 0.017 2 39.9 32.7 0.025 0.018 3 30.1 25.4 0.025 0.012 `
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Owen Kulp Period: 2 Academic Chemistry 11 Partners: Phoebe Jenkins, Isabella Pizzelanti Calculations Molarity of the titrant Average molarity of the titrant ( 0.017 M + 0.018 M + 0.012 M ) 3 = 0.016 M Moles of Acetic acid 0.016 mol HC 2 H 3 O 2 1 L × 0.175 L 1 = 0.028 mol H C 2 H 3 O 2 Molarity of acetic acid 0.028 mol .H C 2 H 3 O 2 1 ×
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