1.) Determine the number of grams of sodium acetate and the amounts in mLs of 6.
ID: 633961 • Letter: 1
Question
1.) Determine the number of grams of sodium acetate and the amounts in mLs of 6.00M acetic acid that you would need to make 50.00mL of a sodium acetate/acetic acid buffer solution at the pH equal to 5.00 in order to make a final concentration of 0.05M.
2) what amounts of 0.2M formic acid and calcium formate will you use in order to make a buffer that has a pH of 4.2? Pka Formic acid =3.7
3) you need to make a formic acid/formate buffer with a concentration of 0.25M. The only salt of the conjugate base formate that you have in the stockroom is calcium (II) formate. So, you weigh out 25 grams of calcium(II) formate and add it to your formic acid solution. what concentration (molarity) of formic acid did you use in making this buffer that has a pH of 4.12.
Explanation / Answer
pH = pKa + log (Salt / Acid)
=> 5 = 4.76 + log (S/A)
=> S/A = 1.738
S + A = 0.05 M
=> 1.738 A + A = 0.05
=> Acid = 0.0183 M
=> Salt = 0.0317 M
=> Moles of Acid = 0.0183 x 0.05 = 0.000915 moles
=> mL = 1000 x 0.000915 / 6 = 0.1525 mL of Acid
Grams of CH3COONa = (50 - 0.1525) x 0.0317 x 82 / 1000 = 0.13 grams
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