Question

need help finishing the chart and answering the questions, help please

6-15: Acid-Base Standardization Titrations provide a method of quantitatively measuring the concentration of an unknown solution. In an volume. (The concentration of an unknown Sitrant can also be determined by titration with an analyte of acid-base titration, this is done by delivering a titrant of known concentration into an analyte of known known concentration and volume.) Titration curves (graphs of volume vs. pl) have characteristic shapes The graph can be used to determine the strength or weakness of an acid or base. The equivalence point of the titration, or the point where the analyte has been completely consumed by the titrant, is identified by the point where the pH changes rapidly over a small volume of titrant delivered. In this assignment, you will determine the molarity of an unknown solution of NaOH by titrating against a primary standard, potassium hydrogen phthalate (KHP). 1. Start Virtual ChemLab, select Acid-Base Chemistry, and then select Acid-Base Standardization from the list of assignments. The lab will open in the Titrations laboratory. 2. Click the Lab Book to open it. Click the Beakers drawer and place a beaker in the spotlight next to the balance. Click on the Balance area to zoom in, open the bottle of KHP by clicking on the lid (Remove Lid). Drag the beaker to the balance to place it on the balance pan and tare the balance. Pick up the Scoop and scoop out some sample by first dragging the scoop to the mouth of the bottle and then pulling the scoop down the face of the bottle. As the scoop is dragged down the face of the bottle it will pickup different quantities of solid. Select the largest sample possible and drag the scoop to the beaker on the balance until it snaps in place and then let go. Repeat this one additional time so you have put two scoops (approximately 2 g) of KHP in the beaker. Record the mass of the sample in the data table on the following page and return to the laboratory. 3. Drag the beaker from the balance to the sink and hold it under the tap to add a small amount of water. Place it on the stir plate and drag the calibrated pH meter probe to the beaker. Add Phenolphthalein as the indicator. 4. The buret will be filled with NaOH. Click the Save button in the Buret Zoom View window so the titration data can be saved. The horizontal position of the orange handle is off for the stopcock. Open the stopcock by pulling down on the orange handle. The vertical position delivers solution the fastest with three intermediate rates in between. Turn the stopcock to one of the fastest positions. Observe the titration curve. When the blue line begins to turn up, double-click the stopcock to turn it off. Move the stopcock down one position to add volume drop by drop. There are two methods for determining the volume at the equivalence point: (1) Stop the titration when a color change occurs. Click the Stop button in the Buret Zoom View. A data link icon will appear in the lab book. Click the data link icon to open the Data Viewer window. Scroll down to the last data entry and record the volume at the equivalence point in the data table. OR (2) Add drops slowly through the equivalence point until the pH reaches approximately 12. Click the Stop button in the Buret Zoom View. A data link icon will appear in the lab book. Click the data link icon to open the Data Viewer window. Click the Copy Data button to copy and paste the data to a spreadsheet. Plot the first derivative of pH vs. volume. The peak will indicate the volume at the equivalence point since this is where the pH is changing the most rapidly as the volume changes. Repeat at least two additional times recording data in the data table. Do not forget to refill the buret with aOH and place the pH meter and indicator in the beaker each time. The molecular weight of KHP is 204.22 g/mol.