nd learning resource from Cengage Learning- Google Chrome ngagenow.com/ilrn/take

Question

nd learning resource from Cengage Learning- Google Chrome ngagenow.com/ilrn/takeAssignment/takeCovalentActivity.do?locator=as...? [Review Topics] Use the References to access important values if needed for this question A 1.00 liter solution contains 0.24 M ammonia and 0.31 M ammonium iodide. If 0.160 moles of sodium hydroxide are added to this system, indicate whether the following statements are true or false. (Assume that the volume does not change upon the addition of sodium hydroxide.) A. The number of moles of NHs y B. The number of moles of NH4 v C. The equilibrium concentration y A. The number of moles of NH will remain the same 5 will increase 2re of H3O will decrease. D. The pH will decrease. E. The ratio of [NH3] / [NH4? will decrease. Submit Answer Retry Entire Group

Explanation / Answer

1 L of 0.24 M ammonia and 0.31 M ammonium iodide is a buffer solution.

pOH of buffer is given by = pKb + log[NH4I]/[NH3]

pOH = 4.75 + log(0.31/0.24)

pOH = 4.8611

pH = 14 - 4.8611 = 9.1389

if you add NaOH solution to the above buffer solution then pH of the resultant is given by,

pOH = pKb + log([NH4I]-[NaOH])/([NH3]+[NaOH])

so the number of moles of NH4+ ions decreses and number of moles of NH3 increases due to strong base NaOH dissociation.

NH4I <-----> NH4+ + I-

NaOH ----> Na+ + OH-

pOH = 4.75 + log((0.31-0.16)/(0.24+0.16))

pOH = 4.324

pH = 14 - 4.324

pH = 9.676

Ratio of [NH3]/[NH4+] initially = 0.24/0.31 = 0.7742

Ratio of [NH3]/[NH4+] = (0.24+0.16)/(0.31-0.16) = 2.67

so,

The number of moles of NH3 will remain the same - False

The number of moles of NH4+ will increase - False

The equilibrium concentration of H3O+ will decreases - True ( pH increases)

The pH will decrease - False

The ratio [NH3]/[NH4+] will decrease - False

Related Questions

Navigate

• Browse (All)
• Browse N
• Subjects

---

---

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