Describe how you would make 250 mL of buffer with a pH of 7.00 using Na3PO4(s) and one of the 1.00 M solutions (HCI or NaOH) so that the concentration of the weak acid in the buffer is 0.130 M. You also have standard glassware available and deionized water. a. Which solution would you choose? b. What are the number of moles of the weak acid and its conjugate base after the addition of the 1.00 M solution? ni, base the initial number of moles of phosphate ions in the flask. c. What volume of the 1.00 M solution should be introduced in the flask? 10.238 mL d. What mass of Na3PO4(s) should be introduced in the flask? 1

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Can you show how to out this calculation in the calculator? Everytime I do it, I get a different answer.

please answer the last 3 sub-parts

need help with both questions pls & thank you!!

Thank you. I'm just confused as what is is the reason 122.1 has to be multiplied by (-45543.23)?

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Application Questions: Answer the following questions. Show all work for calculations and include units and the correct number of significant figures. 1. A solution of cobalt (III) chloride was analyzed using a UV/Vis spectrometer and produced the spectra shown in Fig. 4. What is the best wavelength to use for analyzing the samples? Best wavelength to analyze sample: Absorbance 0.600 0.500 0.400 0.300 0.200 0.100 0.000 375 400 450 425 475 500 525 550 Wavelength (nm) Molarity of FD&C #2 0.000 0.115 0.225 0.350 575 Figure 4. UV/Vis spectra of a cobalt (III) chloride solution for determination of the best wavelength for analysis. 8 600 625 2. Create a graph in Excel and add a linear trendline using the data given below. Calculate the molarity of a solution (to 3 significant digits) with an absorbance of 0.576 using the trendline equation from this graph. Show your work in the box below. DO NOT ATTACH THE FIGURE. Abs 0.002 0.187 0.442 0.699 650 675

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What is  could be the calculated  lambda max of this compound?         315     323     270     285