Question

Which one of the following species is amphiprotic?

Select one:

PO₄^3–(aq)

HCl(g)

HSO₄^–(aq)

Cl^–(aq)

For the system

NH₂OH + CH₃NH₃⁺⇌ CH₃NH₂ + NH₃OH⁺

95% 95 % 5 % 5 %

the state of equilibrium in the system is described by the percentages given. Which of the species is the strongest base in the system?

Select one:

NH₂OH

CH₃NH₃⁺

CH₃NH₂

NH₃OH⁺

An aqueous solution at 25.0 ^oC has an H₃O⁺ concentration of 4.0 × 10^–2 mol L^–1. What is the OH^– concentration of this solution?

Select one:

4.0 × 10^–2 mol L^–1

4.0 × 10^–9 mol L^–1

2.5 × 10^–3 mol L^–1

2.5 × 10^–13 mol L^–1

Hypochlorous acid, HClO, has a pK_a of 7.52. What is the value of K_a for this acid?

Enter your result to 3 significant figures in E format - for example 1.23E-4 represents 1.23x10^-4.

Answer:

A buffer solution was prepared by combining 0.222 M acetic acid (K_a = 1.82 x 10^-5) and 0.278 M sodium acetate. What is the pH of this solution?

Select one:

4.94

4.54

4.84

4.64

Answer 1

1) Which one of the following species is amphiprotic : HSO₄^–(aq)

2) strong base = CH₃NH₂

3)

[H3O+] [OH-] = Kw

4.0 x 10^-2 [OH-]   = 1.0 x 10^-14

answer : 2.5 × 10^–13 mol L^–1

4) pKa = 7.52

    Ka = 10^-7.52

     Ka = 3.02 x 10^-8

answer : Ka = 3.02E-8

5)

pH = pKa + log [base / acid ]

pH = 4.74 + log (0.278 / 0.222)

pH = 4.84

answer : 4.84