Acids, Bases, Thermodynamics

Question 1

the substance NaNO3 is considered a

Answer 1

neutral compound

Question 2

which of these created a solution with pH > 7 but is not strictly an arrhenius base?
CH3NH2
NaOH
CO2
Ca(OH)2
CH4

Answer 2

CH3NH2 is a weak base, it accepts a proton in water forming CH3NH2+ and OH- but does not directly release OH- and is therefore not a arrhenious base.

Question 3

NH3 and (CH3CH2)2NH are considered

Answer 3

weak bases

Question 4

Arrhenius definition of an acid or base

Answer 4

dissociates in water to produce [H3O+] or [OH-]

Question 5

definition of B-L acid-base conjugate pair

Answer 5

two substances that differ by a single proton.
a conjugate acid is formed when a base accepts a proton
a conjugate base is formed when an acid donates a proton

Question 6

a 0.15M solution of chloroacetic acid has a pH of 1.86, what is the value of Ka

Answer 6

0.0014M

Question 7

lactic acid has a pKa of 3.08, what is the dgeree of dissociation of a 0.35M solution of lactic acid

Answer 7

4.9%

Question 8

what is the pH of a 0.050M solution of triethylamine with Kb = 5.3*10^-4

Answer 8

11.71

Question 9

what is the value of Kb for the formate anion when Ka for HCOOH is 2.1*10^-4

Answer 9

4.8*10^-11

Question 10

A solution is prepared by adding 0.1M NaF to 1L of water, what will the solution be

Answer 10

basic

Question 11

which of the following statements about 0.1M NH4Cl in water is correct
a) weakly basic soln
b) strongly basic soln
c) neutral soln
d) acidic soln
e) prediction cannot br made

Answer 11

d acidic soln

Question 12

an aqeous solution is ofund by dissolving the salt formed by the neutralisation of a weak acid and a weak base. what statement is correct
a)weakly basic soln
b) strongly basic soln
c) neutral
d) acidic
e) Ka and Kb must be known

Answer 12

e

Question 13

which of the following is a lewis acid but not a BL acid
a) Fe3+
b) H3O+
c) H2SO4-
d)H2O

Answer 13

a

Question 14

define BL base and include example of something that is a BL base but not an Arrhenius base

Answer 14

A BL base acts as a proton acceptor, all Arrhenius bases are BL bases, but not all BL bases are Arrhenius bases.
Ammonia is a BL base but not an Arrhenius base
NH3 + H20 <-> NH4+ + OH-
Ammonia does not dissociate in water into OH- ions, but accept a proton from water

Question 15

define lewis acid and write an equation for an acid that is a lewis acid and not an arrhenius base

Answer 15

a lewis acid acts as an electron pair acceptor. BF3 is a lewis acid but not Arrhenius or BL acid.
BF3 + NH3 –> BF3NH3

Question 16

do all BL bases have at least one pair of lone electrons

Answer 16

true

Question 17

Consider a water-solution of a weak acid (HA) with an initial concentrat

What are the major species in the 0.010 mol L–1 solution?

Answer 17

HA, H2O

Question 18

Consider a water-solution of a weak acid (HA) with an initial concentration of 0.010 mol L–1
.
The equilibrium concentration of A– was found to be 1.79 ´ 10–5 at 25ºC.

B. write equation for equilibrium governing pH

C. PH

d. Ka for HA

Answer 18

b. HA + H2O <-> A- +H3O+

C. 4.75

D. 3.2*10^-8

Question 19

The stronger the acid

Answer 19

the weaker theconjugate base

Question 20

Explain why it is that the weaker the acid being titrated, the more basic is the pH
at the equivalence point.

Answer 20

at equivalence point, the solution contains the conjugate base of the weak acid. weak acids have stronger conjugate bases, and solutions with stronger bases have more basic pHs

Question 21

Calculate the relative concentration of both 2-ethylbenzoic acid (pKa = 3.79) and
potassium 2-ethylbenzoate that are needed to prepare a buffer of pH = 4.00

Answer 21

1:1.62