Question

PART A:

A particular sample of vinegar has a pHpH of 2.95.

If acetic acid is the only acid that vinegar contains (Ka=1.8×10−5), calculate the concentration of acetic acid in the vinegar. Express your answer using two significant figures.

PART B:

A new potential heart medicine, code-named X-281, is being tested by a pharmaceutical company, Pharma-pill. As a research technician at Pharma-pill, you are told that X-281 is a monoprotic weak acid, but because of security concerns, the actual chemical formula must remain top secret. The company is interested in the drug's Ka value because only the dissociated form of the chemical is active in preventing cholesterol buildup in arteries.

To find the pKa of X-281, you prepare a 0.090 M test solution of X-281 at 25.0 ∘C. The pH of the solution is determined to be 3.00. What is the pKa of X-281?

Express your answer numerically.

Express your answer using two significant figures.

Answer 1

Part -A Vinegar contains acent and only. Let conch of acetic acid in vinegar be - C mol/L. CH3Coon (2-) = 2000 (aq) +4 At t-o : C Hequribrium: Cli-a) ca ca Where & is degree of dissociation of Gceric acid. By law of mass action, Ka - COMC00] [R] . [cnocoons Ka = cax ca CLI-) ka = co? Cgiven Ko = 1.8x10-5) 1 - Ką is very small 1-a ni or x is small and hence can be neglected. => 1C82: 1.8x10-5) - 0 Scanned with CamScanner

Also ph= 2.95 we know that ph= -log ent] = 2.95 Chtla 10-2.25 - 1112 X10-3M .. cx1.12 x10-3 - © dividing 0 by ③ we get as 1.8 X10-5 1.12X10-3 Burning & in ean ② CX 1. 810-5 1.12X10-3 1.1 2x 10-3 cur keep you! upon calculations Tcco.070 M Scanned with CamScanner
Hope you will like my answer:)