Self-Test 6A.3A

[Michellekim1H]

Estimate the concentrations of (a) H3O+ and (b) OH- at 25 C in 6.0 × 10^-5M HI(aq).

The answer for a is 60.μmol⋅L^-1 and for b it's 0.17nmol⋅L^-1. Can someone tell me how to approach this problem?

[Aman Sankineni 2L]

Basically, because hydroiodic acid is a strong acid, it dissociates completely in an aqueous solution. This means that the hydronium concentration is equivalent to the initial molarity of the acid. The back of the book represented this value in micromoles, so instead of just writing it as 6.0x10^-5, they wrote it as 60 micromoles. To get the hydroxide ion concentration, we just divide the autoprotolysis constant (10^-14) by the hydronium ion concentration to get 1.7x10^-10.

[Michellekim1H]

Basically, because hydroiodic acid is a strong acid, it dissociates completely in an aqueous solution. This means that the hydronium concentration is equivalent to the initial molarity of the acid. The back of the book represented this value in micromoles, so instead of just writing it as 6.0x10^-5, they wrote it as 60 micromoles. To get the hydroxide ion concentration, we just divide the autoprotolysis constant (10^-14) by the hydronium ion concentration to get 1.7x10^-10.

Thank you, I actually already figured it out. I kept redoing the problem then I realized that I got the correct answers but the textbook answers just had it in different conversions.