Question

Calculate the percentrage of neutral form of aspirin that is present in the stomach ph 1.

Answer 1

Answer:

The 99.68% of the aspirin is present in the neutral form

Explanation:

Aspirin, Acetylsalicylic acid, is a weak acid with pKa = 3.5

Using Henderson-Hasselbalch equation:

pH = pKa + log [A⁻] / [HA]

Where [A⁻] is the ionized form and HA the neutral form of the acid

Replacing with a pH of stomach of 1.0:

1.0 = 3.5 + log [A⁻] / [HA]

-2.5 = log [A⁻] / [HA]

3.16x10⁻³ = [A⁻] / [HA] (1)

A 100% of aspirin is = [A⁻] + [HA]

100 = [A⁻] + [HA] (2)

Replacing (2) in (1)

3.16x10⁻³ = 100 - [HA] / [HA]

3.16x10⁻³[HA] = 100 - [HA]

1.00316 [HA] = 100

[HA] = 99.68%

The 99.68% of the aspirin is present in the neutral form