A chemist needs a pH 3.5 buffer. Should she use NaOH withformic acid (ka=1.8x10^

Question

A chemist needs a pH 3.5 buffer. Should she use NaOH withformic acid (ka=1.8x10^-4) or with acetic acid (ka=1.8x10^-5)? why?What is the disadvantage of using the other acid? What is the roleof the NaOH? Can someone please help me understand buffers? IA A chemist needs a pH 3.5 buffer. Should she use NaOH withformic acid (ka=1.8x10^-4) or with acetic acid (ka=1.8x10^-5)? why?What is the disadvantage of using the other acid? What is the roleof the NaOH? Can someone please help me understand buffers? IA

Explanation / Answer

For formic acid Ka=1.8x10^-4 pKa = 3.74 Acetic acid (Ka =1.8x10^-5)?                  pKa= 4.74       A buffer canact effictively with in the pH range from pKa - 1 topKa+1. So aceticacid sodium acetate buffercan work effictively in the pH range 3.74 to5.74. So formicacid sodium formate buffercan work effictively in the pH range 2.74 to4.74. She should use NaOH with formicacid to prepare buffer solution with pH 3.5.     

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