You are building a machine to process dates into tasty cookies at a factory. This machine cannot corrode into your date paste, or the taste of the cookies will be ruined. Dates have a natural pH of 6.2 to 6.4. Which conjugate base would you choose to make a buffer solution to test materials for your machine to make sure that they will not ruin the flavor of the cookies

Acid Ka Hydrochloric HCI Acetic CH3COOH 1.8 x 10 Carbonic H2CC 4.3 x 10 Dihydrogen phosphate H-PO, 6.2 x 10 Boric Acid HaBO5.4x 10 T0

a) CI
b) CH3COO
c) HCO3
d) HPO
e) H2BOs

C) HCO₃⁻

Explanation:

pKa of a buffer is defined as -log Ka of the buffer:

For:

Acetic acid: -log 1.8x10⁻⁵ = 4.74

Carbonic acid: -log 4.3x10⁻⁷ = 6.37

Dihydrogen phosphate: -log 6.2x10⁻⁸ = 7.21

Boric Acid: -log 5.4x10⁻¹⁰ = 9.27

The maximum buffering capacity is when pH is ± 1 pKa.

As Carbonic acid has the nearest pKa to desire pH, you must choose HCO₃⁻ as conjugate base.

C) HCO₃⁻

the electrical  conductivity  of asolution  of an electrolyte is measured by determining the resistance of thesolution  between two flat or cylindrical electrodes separated by a fixed distance.

a electronegativity decreases beacuse the size of nucleus is bigger.