305 Critical Thinking Problem Set-Chapter 10 cabel the Bronsted-Lowry acids and

Question

305 Critical Thinking Problem Set-Chapter 10 cabel the Bronsted-Lowry acids and bases in the following equations, and tell which substances are conjugate acid-base pairs. 6) An aqueous 0.10 M solution of the deadly poison hydrogen cyanide, HCN, has a phH of s.2 a) Is HCN acidic or basic? Is it strong or weak? b) What is the [HO'T c What is the [OH] and the pOH? 7) Human spinal fluid has a pH of 7.4 a) Approximately what is the H,O* concentration of spinal fluid? b) What is the [OH] and the pOH? 10.2

Explanation / Answer

5) In Bronsted-Lowry concept of acids and bases, an acid is a proton (H+) donor while a base is a proton (H+) acceptor.

a) CO32-(aq)[base] + HCl(aq) [acid] ----> HCO3-(aq)[conjugate acid] + Cl-(aq) [conjugate base]

b) H3PO4 (aq) [acid] + NH3(aq)[base] -----> H2PO4-(aq)[conjugate base] + NH4+(aq) [conjugate acid]

c) NH4+(aq) [acid]+ CN-(aq) [base]<----> NH3(aq) [conjugate base]+ HCN (aq) [conjugate acid]

d) HBr(aq)[acid] + OH-(aq) [base]-----> H2O(l)[conjugate acid] + Br-(aq) [conjugate base]

e) H2PO4- (aq)[acid] + N2H4 (aq)[base] <----> HPO42-(aq)[conjugate base] + N2H5+(aq) [conjugate acid]

6)

a) The given pH of HCN is 5.2. The pH value less than 7 indicates that HCN is acidic. Also,HCN is a weak acid.

b) [H3O+] = 10-pH = 10-5.2 = 6.31 x 10-6 M

c) We have the relation as--

pH + pOH = 14

=> pOH = 14-pH = 14-5.2 = 8.8

Now, [OH-] = 10-pOH = 10-8.8 = 1.58 x 10-9 M

7)

a) Given pH of human spinal fluid = 7.4

so, [H3O+] =10-pH = 10-7.4 = 3.98 x 10-8 M

b) We have the relation as, pH + pOH =14

=> pOH = 14-pH = 14 - 7.4 = 6.6

Now, [OH-] = 10-pOH = 10-6.6 = 2.51 x 10-7 M

Related Questions

Navigate

• Browse (All)
• Browse 3
• Subjects

---

---

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