Final

Question 1

Buffer Capacity

Answer 1

amount of strong acid or base that can be consumed by the buffer; the ability of the buffer to consume acid is limited by the amount of A- present in the original buffer (and vice versa)

Question 2

Buffers are effective over a pH range of…

Answer 2

pKa +/- 1; because

log(9/1)= +0.99 and log(1/9)= -0.99

Question 3

Phosphate Buffer used in Expt. 5 was made up of…

Answer 3

0.05M K2HPO4 and 0.05M KH2PO4

Question 4

Making a Buffer Solution: 2 equations/2 unknowns

Answer 4

1) H-H equation

2) [HA] + [A-] = total concentration of buffer

Question 5

Calculating Buffer Capacity

Answer 5

Molarity X Volume = Moles consumed

Question 6

NO3- and (Ch3Coo-) are always….

Answer 6

soluble

Question 7

Cl-, Br-, I- are soluble except with..

Answer 7

Ag+, Hg22+, Pb2+

Question 8

SO42- soluble except with..

Answer 8

Sr2+, Ba2+, Hg22+, Pb2+

Question 9

NH4+ is always…

Answer 9

soluble

Question 10

(CO32-) and (PO43-) insoluble except with…

Answer 10

NH4+, and Group 1A

Question 11

(OH-) and S2- insoluble except with…

Answer 11

NH4+, Group 1A, Ba2+, Ca2+, Sr2+

Question 12

Q > Ksp

Answer 12

ppt. forms

Question 13

Q

Answer 13

no ppt. forms, dissolved ions

Question 14

Q= Ksp

Answer 14

ppt. re-dissolves

Question 15

log(Ksp)=

Answer 15

pKsp

Question 16

the larger pKsp the…

Answer 16

less soluble (more ppt.) and more stable ppt.

Question 17

pKsp

Answer 17

difficult to form ppt. unstable

Question 18

pKsp ~6-7

Answer 18

easily formed ppt. and stable

Question 19

pKsp > 10

Answer 19

quantitative ppt.

Question 20

pH and ppt.

Answer 20

ppt. are often pH dependent bc anions are often bases that can be protonated when pH is in a range of ~1-13. (think about titration)
(C2O4)2- –> oxalate–> behaves this way

Question 21

NH4+ or Thiosulfate added to anions

Answer 21

acts to form complex ions, and dissolves ppt.

Question 22

Al3+ + OH-

and then with calmagite

Answer 22

ppt. formed, and with excess NaOH, the ppt. dissolved

with calmagite–> clear pink color

Question 23

Ba2+ + OH-

and then with calmagite

Answer 23

ppt. film, with calmagite –> creamy pink

Question 24

Ca2+ + OH-

and then with calmagite

Answer 24

small ppt. film,

calmagite–> pink color

Question 25

Mg2+ + OH-

and then with calmagite

Answer 25

small ppt.

with calmagite–> darkest of all in pink color

Question 26

Al3+ + (C2O4)2-

Answer 26

no rxn

Question 27

Ba2+ + (C2O4)2-

and HNO3

Answer 27

ppt. formed

5 drops HNO3 to dissolve (LESS STABLE)

Question 28

Ca2+ + (C2O4)2-

and HNO3

Answer 28

ppt formed

16 drops HNO3 to dissolve

Question 29

Mg2+ + (C2O4)2-

Answer 29

no rxn

Question 30

Al3+ + (SO4)2-

Answer 30

no rxn

Question 31

Ba2+ + (SO4)2-

Answer 31

ppt.

Question 32

Ca2+ + (SO4)2-

Answer 32

no rxn

Question 33

Mg2+ + (SO4)2-

Answer 33

no rxn

Question 34

Al3+ + phenol red

Answer 34

YELLOW

Question 35

Ba2+ + phenol red

Answer 35

pink

Question 36

Ca2+ + phenol red

Answer 36

pink

Question 37

Mg2+ + phenol red

Answer 37

pink

Question 38

Br- + AgNO

+ NaS2O3

Answer 38

yellowy ppt

NaS2O3–> dissolved ppt

Question 39

Cl- + AgNO

+ NaS2O3

Answer 39

white ppt

NaS2O3–> dissolved ppt

Question 40

I- + AgNO

+ NaS2O3

Answer 40

ppt

NaS2O3–> no change. still ppt.

Question 41

CH3COO- + Fe(NO3)3

+ HNO3

Answer 41

orange in color

HNO3–> colorless

Question 42

Water + Fe(NO3)3

+ HNO3

Answer 42

yellow color

HNO3–> colorless

Question 43

Flame Test

Answer 43

Na+ –> bright orange flame towards top of flame

Question 44

Mg2+ & Al3+

Answer 44

Cant be in same solution

Question 45

Mg2+ & Ca2+

Answer 45

cant be in same solution

Question 46

Halides in solution (as anions)

Answer 46

ONLY ONE (Br-, I-, Cl-)