Label each reactant and product in this reaction as a Bronsted acid or base. Wri

Question

Label each reactant and product in this reaction as a Bronsted acid or base. Write the balanced chemical equation for the reaction of the weak acid HCN with water. Include the phase of each species. Consider three generic acids with the following relative stengths: HX > HY > HZ Rank the strengths of their conjugate bases. Consider three generic acids with the following relative stengths: HX > HY > HZ Rank the strengths of their conjugate bases. Ka of a monoprotic weak acid is 2.81 times 10 3. What is the percent ionization of a 0.149 M solution of this add?

Explanation / Answer

1) CH3OH + OH- -------> CH3O- + H2O

acid base base acid

2) HCN (aq) + H2O (l) --------------> H3O+ (aq) + CN- (aq)

Do not subscript the phases. Write as above.

3) Z- > Y- > X-

The stronger the acid, the weaker the conjugate base. Similarly, weaker the acid, the stronger the conjugate base.

4) Let the weak acid be HA.

HA ---------------------> H+ + A-

I 0.149 0 0

C -x +x +x

E 0.149 - x +x +x

Ka = x2/ (0.149-x) => 2.81 x 10-3 = x2 / (0.149-x)

The quadratic expression obtained for this is,

x2 +(2.81 x 10-3)x - (4.187 x 10-4) =0

x = -0.0219

X = 0.0191

So, we use x = 0.0191

So, [H+] = [A-] = 0.0191

% ionisation = ([A-] / [HA] ) x 100 = 0.0191 / 0.149 x 100 = 12.81%

Related Questions

Navigate

• Browse (All)
• Browse L
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.