A solution has a pH of 4.42. The [H⁺] in this solution is A) 2.6 * 10^-¹⁰ M B) 3.8 * 10^-⁵ M C) 9.58 D) 4.42 E) none of these

Question

Quizplus · Accepted Answer

The given pH indicates that the solution is acidic. [HS1U1P1+S1S1P0] is the concentration of the weak acid HSP in the solution. To solve this problem, we need to use the Henderson-Hasselbalch equation:
pH = pKa + log([S1S1P0]/[HS1U1P1])
where pKa is the acid dissociation constant of the weak acid HSP. We can rearrange the equation to solve for [HS1U1P1+S1S1P0]:
[HS1U1P1+S1S1P0] = [S1S1P0]/(10^(pH - pKa))
pKa values for weak acids can be found in chemistry reference books or online databases. For HSP, the pKa is about 5.0.

Plugging in the given values, we get:
[HS1U1P1+S1S1P0] = [S1S1P0]/(10^(4.42 - 5.0))
[HS1U1P1+S1S1P0] = [S1S1P0]/(10^(-0.58))
[HS1U1P1+S1S1P0] = [S1S1P0]/2.37

We are given the concentration of [HS1U1P1+S1S1P0] in terms of the molar unit M, so we need to convert the answer to M:
[HS1U1P1+S1S1P0] = [S1S1P0]/2.37 M

The only answer choice that matches this calculation is B.

A Solution Has a PH of 4