COULD OSMEONE PLEASE GIVE A STEP BY STEP EXPLANATION TO WHY THE ANSWERS ARE THE

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COULD OSMEONE PLEASE GIVE A STEP BY STEP EXPLANATION TO WHY THE ANSWERS ARE THE ANSWERS BELOW? I DONT UNDERSTAND THE STEPS OR LOGIC BELOW

Question 4. Answer the following two questions about a weak organicacid solution (pKa 4.25) that readily absorbs photons in the visible region. molar absorptivity (M cm form blue (490 nm) orange (590 nm) negligible 210 HA negligible 500 a. What color would the solution appear, when pH 310.00? 100% in the deprotonated form, and will be orange in color. b. You prepare 250.0 mL of a buffered solution whose formal concentration is 0.150 M What percentage of the molecules will be blue in color if you adjust the pH to 4.76? 10 4.76-4.25 molecules and 76.4%A molecules 3.24...23.6% HA HA LA 0.150 Mx0.764 -0.115 M HA 0.150 MX 0.236- 0.035 M

Explanation / Answer

Answer 4 a)

In first part,when solution is in totally deprotonated form ,it will absorb mostly in blue region and solution will appear orange in colour.

Answer b)

In second part we just have to apply Handerson Hasselbelch equation

pH=PKa + log10 [A-]/[HA]

PH=4.76 PKa =4.25

4.76-4.25=log [A-]/[HA]

0.51=log [A-]/[HA]

[A-]/[HA] =10 ^0.51

=3.2359

rOUNDING OFF GIVES 3.234

That means 23.6 % of HA and 76.4 % A-

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