ch 15-17 Flashcards Preview

Chemistry (Gen II) > ch 15-17 > Flashcards

Flashcards in ch 15-17 Deck (58):
1

polyprotic acid

has more than one ionizable proton
-diprotic= Ka1>Ka2 (more difficult to remove H+ ion from negatively charged anion)
-triprotic= phosphoric acid, citric acid

2

acid-base properties of salts

the weak acid/ base is what hydrolyzes the water
-if basic ion breaks up water, acidic salt solution results
(A-)B+ + H2O -> BOH + H+ (B=base)
(B+)A- + H2O -> HA + OH- (A=acid)

3

finding pH of salt solutions

1- write the balanced chem equilibrium equation for basic anion or acidic cation
2- determine K
3- solve equilibrium problems for [H3O+] and [OH-]

4

common ion effect

shift in position of an equilibrium caused by the addition of an ion taking part in the reaction
-if the concentration of one ion produced in the ionization of a weak electrolyte is increased, the weak electrolyte ionizes less

5

buffer

solution containing a weak acid OR weak base with the salt of the acid or base

6

henderson- hasselbalch equation

equation to calculate pH of solution in which the concentrations of acid and conjugate base are known
pH= pKa +log ([base]/[acid])

7

pH buffer

solution that resists changes in pH when acids or bases are added to it, typically a solution of a weal acid and its conjugate base

8

buffer capacity

extent to which pH changes are inversely related to buffer concentration
-quantity of acid or base that a pH buffer can neutralize within a defined range
-the greater the concentrations, the greater the buffering capacity
-the greater the buffering capacity, the greater the ability to withstand addition of acids/ bases without significant change in pH

9

mole ratio

alter to make a particular buffer better able to handle large quantities of a base/acid

10

pH indicator

water-soluble weak organic acid that changes color as it ionizes- used to determine the pH in solution
**midpoint of range of pH= pKa
-inverted curve= strong or weak basic analyses with strong acid in titration

11

Phenol red

weak acid- pKa= 7.6, yellow= unionized (pH 6.6), purple = ionized (pH 8.6)
-pH indicators work over specific pH range (midpoint of their range= pKa)

12

lewis acid

substance that accepts a lone pair of electrons
-transition metals

13

lewis base

substance that donates a lone pair of electrons
-nitrogen bases and derivatives, OH-, O2-

14

equivalence point

moles acid= moles base

15

end point

one drop after equivalence point (indicator shows change)

16

coordinate bonds

a covalent bond is formed when one anion or molecule donates a pair of electrons to another ion/ molecule- interaction between lone pair and empty orbital = ex of Lewis acid-base behavior

17

complex ions

ionic species consisting of a metal ion bonded to one or more Lewis base

18

ligrand

a Lewis base bonded to central metal ion of a complex ions

19

formation constant (Kf)

an equilibrium chnstant describing the formation of a metal complex from a free metal ion and its ligands
Kf= [products]/ [reactants]

20

solubility product constant

an equilibrium constant that describes the formulation of a saturated solution of a slightly soluble salt

21

solubility

grams solute per 100 mL of solution

22

molar solubility

moles solute per L of solution

23

binary acid strength

the strength of HX acid increases as electronegativity decreases

24

oxoacid strength

the more oxygen atoms, the stronger the acid
HXO acids have increased strength as electronegativity increases

25

carboxylic acid strength

increased number of electronegative elements, increased strength

26

strong bases

hydroxides of group one or two

27

weak bases

usually contain nitrogen- reach equilibrium before all base is used

28

conjugate acid-base

differ by one proton- strong acids/ bases have very weak conjugate bases/ acids
-weak acids have weak conjugate bases

29

leveling effect

all strong acids/ bases are the same strength because there cannot be over 100% hydronium ion conc
-weak acids/ bases are differentiated in strength by the fraction of their molecules that accept H+

30

degree ionization

*** degree ionization of weak acids increases with decreasing acid concentration

31

RICE tables

- for weak acids and bases
-also for very dilute strong acids/ bases (calculate auto ionization of water)

32

salt solutions

= acidic if the cation is the conjugate acid of a weak base and the anion is the conjugate base of a strong acid
=basic if the anion is conj base of weak acid and cation is conj acid of strong base

33

common ion effect

shift in position of equilibrium caused by addition of an ion taking part in the reaction

34

Henderson hasselbach equation

used when there are separate sources of both weak acid and conjugate base- for calculating pH

35

pH buffers

ideal= similar cones of each constituent component... when the ratio of conjugate pair is around 1, the pH of the buffer is close to the pKa of the weak acid***
-used to pick buffer that keeps pH around pka

36

buffer capacity

greater the ability to withstand acid/ base additions without significant changes in pH
-the greater the concentrations of conjugate pair components, the greater the buffer capacity

37

midpoint on titration curve

pH= pKa of acid
-titrations with base analytes and strong acid titrants have inverted curves

38

lewis acid base

accepts lone pair of e= acid/ donates lone pair of e= base

39

coordinate bonds

shared electrons of Lewis acid and base pairs= covalent

40

ligands

electron pair donors in complex ions

41

formation constant (kf)

describes formation of complex ion: formation of metal complex from free metal ion and its ligands

42

solubility product (constant)

ksp= [mg][OH]^2

43

Q= ion product

product of concentrations of ions in solution after each is raised to subscript
-if Q>ksp reaction favors reactants (precipitates)
-if Q

44

electrochemical cell

converts chemical energy into electrical work or energy

45

anode

electrode at which oxidation half reaction occurs (loss of e)

46

cathode

electrode at which reduction half reaction occurs (gain of e)

47

standard reduction potential (Eo)

volts- potential of a reduction half reaction in which all reactants and products are in their standard states (at 25 C)

48

standard cell potential (Eo cell)

measure of how forcefully an electrochemical cell can pump electrons through external circuits
-Eo cell is a measure of emf

49

electromotive force (emf)

voltage= force pushing electrons through external ciruit

50

Ecell

cell potential= emf with which an electrochemical cell can pump electrons through external circuit

51

delta G

=change in free energy
negative in voltaic cells because the reaction is spontaneous

52

faraday constant

magnitude of electric charge of one mole of electrons

53

standard hydrogen electrode

reference electrode based on the half reaction 2H+ + 2e- --> H2 = 0V
***the measure of Ecell for any voltaic cell with SHE on either end is the potential produced by the non-SHE electrode alone

54

oxidizing agents and Eo

the more positive Eo is, the higher the reducing ability is, and therefore the better the oxidizing agent it is

55

voltaic cell

spontaneous cell reaction, does work on surroundings

56

electrolytic cell

external source of E; does work on system

57

concentration cell

same substances in anode and cathode- difference in concentration
- anode= lower conc; cathode= higher
-Eo cell of conc cells is always 0
-e travel from lower to higher conc

58

fuel cell

voltaic cell based on oxidation of continuously supplied fuel- the reaction is the equivalent of combustion but chemical energy is converted to electrical energy