Homework #5

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Page ID: 42484

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Due on Feb 19 (Friday)

Q1

One example for NH₃ as a conjugate acid: \(\ce{NH2- + H+ ⟶ NH3}\); as a conjugate base: \(\ce{NH4+}(aq)+\ce{OH-}(aq)⟶\ce{NH3}(aq)+\ce{H2O}(l)\)

Show by suitable net ionic equations that each of the following species can act as a Brønsted-Lowry acid:

HCl
NH₃
CH₃CO₂H
\(\ce{HPO4^{2-}}\)
\(\ce{HSO_4^-}\)

Q2

Calculate the pH and the pOH of each of the following solutions at 25 °C for which the substances ionize completely:

0.014 M NaOH
0.0031 M Ca(OH)₂

Q3

Calculate the pH of each of the following solutions at 25 °C. The values of K_a and K_b are found in lecture slides. Verify assumptions you make.

0.50 M C₂H₅NH₂
0.0010 M HCOOH

Q4

The strongest base or strongest acid is the one with the larger K_b or K_a, respectively. The values of K_a and K_b are found in lecture slides.

Which is the stronger acid, \(\ce{NH4+}\) or HCN?
Which is the stronger base, C₅H₅N or \(\ce{C_6H_5COO^-}\)?