Book: Key Terms: Ch. 19

Question 1

acid-base buffer

Answer 1

A solution that lessens the impact on its pH of the addition of acid or base.

Question 2

acid-base titration curve

Answer 2

A plot of pH vs. volume of titrant added.

Question 3

buffer capacity

Answer 3

A measure of the strength of a buffer. In absolute concentrations, the more concentrated the buffer components, the greater the capacity. In terms of relative concentrations, the closer the component concentrates are to each other, the greater the capacity.

Question 4

buffer range

Answer 4

The pH range over which the buffer is effective and is also related to the relative buffer-component concentrations. In general, buffers have a usable range within ±1 pH unit of the pK_a of the acid component.

Question 5

common-ion effect

Answer 5

The common-ion effect occurs when a given ion is added to an equilibrium mixture that already contains that ion, and the position of equilibrium shifts from forming it.

Question 6

complex ion

Answer 6

A central metal ion covalently bonded to two or more anions or molecules, called ligands.

Question 7

equivalence point

Answer 7

Occurs when the number of moles of added OH- equals the number of moles of H3O+ originally present. At this point, the solution is neutral.

Question 8

Henderson-Hasselbaltch equation

Answer 8

pH = pK_a + log ( [base] / [acid])

Question 9

formation constant K_f

Answer 9

K_f is the equilibrium constant expression for the following reaction of complex ions and ligands in water:
X (H2O) + Y ⇌ XY + H2O

Question 10

ligand

Answer 10

Ionic ligands are what complex ions bond to; examples of ionic ligands include hydroxide, chloride, and cyanide, while molecular ligands include water, carbon, monoxide, and ammonia.

Question 11

selective precipitation

Answer 11

In this process, a solution of one precipitating ion is added to a solution of two ionic compounds until the Q_sp of the more soluble compound is almost equal to its K_sp. As a result the max amount of the less soluble compound precipitates, but none of the more soluble compound does.

Question 12

solubility-product constant K_sp

Answer 12

For a slightly soluble compound M_p X_q composed of the ions M(n+) and X(z-), the ion-product expression at equilibrium is Q_sp = [M(n+)]^p [X(z-)]^q = K_sp