Kw, Ka and Kb

How would you calculate K_b for the formate ion (HCOO^–), given that the K_a for formic acid (HCOOH) is 1.8 × 10^–4? (K_w=1.0 × 10^–14)

• K_b = K_a × K_w

• K_b = K_w / K_a

• K_b = K_a / K_w

• K_b = K_w + K_a

The magnitude of Kw indicates that ______________.

• water autoionizes very slowly

• water autoionizes very quickly

• water autoionizes only to a very small extent

• the autoionization of water is exothermic

In which of the following aqueous solutions does the weak acid exhibit the highest percentge of ionization?

• .01 M HC₂H₃O₂ . (K_a 1.8 x 10 ^-5)

• .01 M HNO₂ . ( Ka =4.5 x 10 ^-4)

• .01 M HClO . (Ka= 3.0 x 10 ^-8)

• .01 M HF (Ka= 6.8 x 10 ^-4)

Of the following, which is the strongest acid

• HClO

• HClO₂

• HClO₃

• HClO₄

HA is a weak acid. Which equilibrium corresponds to the equilibrium constant K_b for A^-?

• HA _(aq) + H₂O _(l) <---> H₂A^+ _(aq) + OH^-_(aq)

• A^- _(aq) + H₃O⁺ _(aq) <---> HA _(aq) + H_2O _(l)

• HA _(aq) + OH^- _(aq) <---> H₂O _(l) + H^+ _(aq)

• A^- _(aq) + H₂O _(l) <---> HA _(aq) + OH^- _(aq)

• A^- _(aq) + OH^- _(aq) <---> HOA^2- _(aq)

What is the conjugate base of HClO₄?

• H⁺

• Cl^-

• ClO₃^-

• ClO₄^-

What is the closest pH to a solution with a [H⁺] = 2.5 x 10^-10?

• 2.5

• 3.0

• 4

• 9

The [OH^-] = 4.0 x 10^-9, what is the pH of the solution?

• 9.0

• 5.7

• 8.3

• 4.3

Which acid produces the strongest conjugate base?

• HClO₄ (Ka= 1.0 x 10⁷)

• HCN (Ka= 4.0 x 10^-10)

• H₃PO₄ (Ka= 7.5 x 10^-3)

• H₂CO₃ (Ka = 4.2 x 10^-7)

Tags

NGSS.HS-PS1-1

Which relationship relates Ka, Kb and Kw?

• Kw = Ka + Kb

• Kw = Kb/Ka

• Ka = Kw + Kb

• Kb = Kw/Ka