Chapter 16 Part 3

Question 1

What is the relationship between K_a and K_b for a weak conjugate acid/base pair?

Answer 1

K_a x K_b = K_w

K_w is the ion product of water, typically 1.0 x 10^-14 at 25°C.

Question 2

For a conjugate acid-base pair at 25˚C, what is the relationship involving pK_a and pK_b?

Answer 2

pK_a + pK_b = pK_w = 14.00

Question 3

How do you calculate K_b if K_a is known for a conjugate acid?

Answer 3

K_b = K_w / K_a

Question 4

What is the behavior of weak polyprotic acids regarding H+ loss?

Answer 4

Each H+ loss is treated as an independent event.

Question 5

What notation is used for the equilibrium constants of successive H+ loss in polyprotic acids?

Answer 5

K_a1 for 1st H+ lost, K_a2 for 2nd H+ lost, K_a3 for 3rd H+ lost

Question 6

How do the equilibrium constants K_a1, K_a2, and K_a3 relate in weak polyprotic acids?

Answer 6

K_a1 > K_a2 > K_a3

Question 7

What is the typical difference in equilibrium constant values between steps in polyprotic acids?

Answer 7

Often 10^3 or greater.

Question 8

How does acidity of binary acids (HX) change down a group?

Answer 8

Acidity increases down a group as the non-hydrogen element increases in size.

Question 9

List the order of acidity for binary acids: HI, HBr, HCl, HF.

Answer 9

HI > HBr > HCl > HF

Question 10

How does acidity of binary acids change across a period?

Answer 10

Acidity increases across a period as electronegativity increases.

Question 11

How does the acidity of oxoacids change with central atom electronegativity?

Answer 11

Acidity increases with increasing electronegativity of the central atom.

Question 12

What is the trend in acidity for oxoacids with the same central atom and varying oxidation states?

Answer 12

Acidity increases with increasing oxidation number of the central atom.

Question 13

how to find ka is kb is known?

Answer 13

kw/kb