(1) Answer the following questions about electrolyte solutions. Round the numerical answers to two significant figures.

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1 Answer The Following Questions About Electrolyte Solutions Round The Numerical Answers To Two Significant Figures 1 (141.18 KiB) Viewed 29 times

1 Answer The Following Questions About Electrolyte Solutions Round The Numerical Answers To Two Significant Figures 2 (103.98 KiB) Viewed 29 times

(1) Answer the following questions about electrolyte solutions. Round the numerical answers to two significant figures. (a) Calculate ionic strengths (I) of the following electrolyte solutions. i) 0.10 M NaCl ii) 0.50 M Na2SO4 iii) 0.20 M MgSO4 + 0.15 M KC1 (b) The concentrations of an acid (HA) and its conjugate base (A¯) are shown by [HA] and [A-], and their dissociation constant is shown by pKa. How is the pH of the solution expressed using [HA], [A-], and pKa? (c) HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) is commonly used for a buffer solution in biochemical experiments and its pKa is 7.56 at room temperature. A buffer solution is now prepared by dissolving 100 mmol HEPES in 1 L water and adjusting the pH to 7.56. Answer how the pH of the solution changes when 30 mmol of HCl is added here, based on the result of (b) without considering the volume change of the solution upon the addition of HCl. (2) Spectroscopic analysis methods provide various insights into the structure and dynamics of molecules. Answer the following questions about spectroscopic analysis methods. (a) "Fourier-transform infrared spectroscopy" and "Raman spectroscopy" are the major spectroscopic methods for investigating the vibrational states of samples. In the four normal vibrations shown below, choose the IR and Raman active modes from them, and explain the reason. i) iii) iv)

Absorption and fluorescence spectra of anthracene (C14H₁0) are shown in the right figure. Briefly answer the following questions (b) and (c), with text and figures. (b) Explain the reason why the fluorescence spectrum of anthracene is a mirror image of the absorption spectrum. Absorption and fluorescence intensity 300 2 of absorption of fluorescence Absorption 340 Anthracene OOO Fluorescence 380 420 Wavelength (nm) 460 (c) Explain the reason why the longest-wavelength peak of the absorption spectrum (20 transition of absorption) does not match with the shortest-wavelength peak of the fluorescence spectrum (2o transition of fluorescence), and the latter appears on the longer-wavelength side compared to the former.