Chem.125-126: Sept.17-23

Agenda One hour discussion of E1(Questions, p.48) Two hours of E2; E2 = two session 5 hour lab

Preparation Pre-lab Report (p.63) for E2 completed Discussion Presentation for E1 completed Pre-lab reading and studies for E2 completed

E1:Discussion Preparation

Refer to the discussion grading rubricks, pp. 46-47. Refer to the discussion information, page 233 andposted on CTools. Send presentation to GSI and obtain feedback

E2: Electrons and Solution Color

Session 1: Two Hour Lab Agenda* Complete Part 1(Solution preparation) Complete Part 2 Prepare Part 4 (Solution dilutions) or startPart 3 as indicated by GSI * See Student Information Sheet on Ctools.

Session 2: Three Hour Lab Agenda Complete Parts 3, 4, and 5

E2: Electrons and Solution Color

Is salt solution color predictable based on:• the position of the metal ion’s element in the

periodic table?• the metal ion’s electron configuration (Fig. 3, p. 223)?• the metal ion’s ionic radius (Ionic Sizes, p. 255)?• Its absorption and transmission of visible light?

Goals: See discussion questions (p.73)

Part 1. Preparation and Color of Solutions

1H+

Hydrogen IIIA IVA VA

3Li+

Lithium

4Be

Beryllium

1 1Na+

Sodium

1 2Mg2+

Magnesium IIIB IVB VB VIB VIIB VIIIB ! VIIIB IB IIB

1 3Al3+

Aluminum

1 9K+

Potassium

2 0Ca2+Calcium

2 1Sc

Scandium

2 2Ti

Titanium

2 3V

Vanadium

2 4Cr3+

Chromium

2 5Mn

Manganese

2 6Fe3+Iron

2 7Co2+Cobalt

2 8Ni2+Nickel

2 9Cu2+Copper

3 0Zn2+Zinc

3 1GaGalium

3 2Ge

Germanium

3 7Rb

Rubidium

3 8Sr2+

Strontium

3 9YYitrium

4 0Zr

Zircon-ium

4 1NbNiobium

4 2Mo

Molyb-denum

4 3Tc

Technetium

4 4Ru

Ruthenium

4 5Rh

Rhodium

4 6Pd

Palladium

4 7Ag+Silver

4 8Cd2+

Cadmium

4 9InIridium

5 0

Sn2+

Tin

5 1Sb

Antimony

5 5Cs

Cesium

5 6Ba2+Barium

5 7La*

Lanthanum

7 2Hf

Hafnium

7 3TaTantalum

7 4W

Tungsten

7 5Re

Rhenium

7 6Os

Osmium

7 7IrIridium

7 8PtPlatinum

7 9AuGold

8 0Hg2+

Mercury

8 1TlThallium

8 2

Pb2+Lead

8 3BiBismuth

Teams prepare solutions with different metal ionsRecord the color of solutions.

Solution Color Solutions with ions of the same metal element withdifferent ion charges may have different colors.

DEMO: V2+ vs. V3+ etc.

1H+

Hydrogen IIIA IVA VA

3Li+

Lithium

4Be

Beryllium

1 1Na+

Sodium

1 2Mg2+

Magnesium IIIB IVB VB VIB VIIB VIIIB ! VIIIB IB IIB

1 3Al3+

Aluminum

1 9K+

Potassium

2 0Ca2+Calcium

2 1Sc

Scandium

2 2Ti

Titanium

2 3V

Vanadium

2 4Cr3+

Chromium

2 5Mn

Manganese

2 6Fe3+Iron

2 7Co2+Cobalt

2 8Ni2+Nickel

2 9Cu2+Copper

3 0Zn2+Zinc

3 1GaGalium

3 2Ge

Germanium

3 7Rb

Rubidium

3 8Sr2+

Strontium

3 9YYitrium

4 0Zr

Zircon-ium

4 1Nb

Niobium

4 2Mo

Molyb-denum

4 3Tc

Technetium

4 4Ru

Ruthenium

4 5Rh

Rhodium

4 6Pd

Palladium

4 7Ag+Silver

4 8Cd2+

Cadmium

4 9InIridium

5 0Sn2+Tin

5 1Sb

Antimony

Periodic Table with common metal ion charges.

Salt solution preparation

Calibration line

Volumetric flasks

Chem.125/126 Mascot

__________________________________________________________

Moles and the Periodic Table?

?

National Mole Day: October 23. Why?

1

H1.008

3

Li6.940

11

Na22.991

19

K39.100

37

Rb85.48

55

Cs132.91

87

Fr(223)

4

Be9.013

12

Mg24.32

20

Ca40.08

38

Sr87.63

56

Ba137.36

88

Ra226.05

58

Ce140.13

5

B10.82

13

Al26.98

31

Ga69.72

49

In114.82

81

Tl204.39

90

Th232.05

6

C12.011

14

Si28.09

32

Ge72.60

50

Sn118.70

82

Pb207.21

7

N14.008

15

P30.975

33

As74.91

51

Sb121.76

83

Bi208.9

8

O15.999

16

S32.06

34

Se78.96

52

Te127.61

84

Po(209)

9

F19.00

17

Cl35.457

35

Br79.916

53

I126.91

85

At(210)

10

Ne20.183

18

Ar39.944

36

Kr83.80

54

Xe131.30

86

Rn(222)

2

He4.003

21

Sc44.96

22

Ti47.90

23

V50.95

24

Cr52.01

25

Mn54.94

26

Fe55.85

27

Co58.94

28

Ni58.71

29

Cu63.54

30

Zn65.38

39

Y88.92

40

Zr91.22

41

Nb92.91

42

Mo95.95

43

Tc(99)

44

Ru101.1

45

Rh102.9

46

Pd106.4

47

Ag107.88

48

Cd112.41

57†

La138.92

72

Hf178.50

73

Ta180.95

74

W183.86

75

Re186.22

76

Os190.2

77

Ir192.2

78

Pt195.09

79

Au197.0

80

Hg200.61

89††

Ac(227)

104

Rf(261)

105

Ha(262)

106

--(263)

59

Pr140.92

60

Nd144.27

61

Pm(145)

62

Sm150.35

63

Eu152.35

64

Gd157.26

91

Pa(231)

92

U238.07

93

Np(237)

94

Pu(242)

95

Am(243)

96

Cm(245)

65

Tb158.93

97

Bk(249)

66

Dy162.51

67

Ho164.94

68

Er167.2

69

Tm168.94

70

Yb173.04

71

Lu174.99

98

Cf(251)

99

Es(254)

100

Fm(255)

101

Md(256)

102

No(254)

103

Lr(257)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Where are moles represented on the periodic table?

Mole

= mol = 6.02 x 1023 item

= atomic wt (g) = formula wt (g)

1

H1.008

3

Li6.940

11

Na22.991

19

K39.100

37

Rb85.48

55

Cs132.91

87

Fr(223)

4

Be9.013

12

Mg24.32

20

Ca40.08

38

Sr87.63

56

Ba137.36

88

Ra226.05

58

Ce140.13

5

B10.82

13

Al26.98

31

Ga69.72

49

In114.82

81

Tl204.39

90

Th232.05

6

C12.011

14

Si28.09

32

Ge72.60

50

Sn118.70

82

Pb207.21

7

N14.008

15

P30.975

33

As74.91

51

Sb121.76

83

Bi208.9

8

O15.999

16

S32.06

34

Se78.96

52

Te127.61

84

Po(209)

9

F19.00

17

Cl35.457

35

Br79.916

53

I126.91

85

At(210)

10

Ne20.183

18

Ar39.944

36

Kr83.80

54

Xe131.30

86

Rn(222)

2

He4.003

21

Sc44.96

22

Ti47.90

23

V50.95

24

Cr52.01

25

Mn54.94

26

Fe55.85

27

Co58.94

28

Ni58.71

29

Cu63.54

30

Zn65.38

39

Y88.92

40

Zr91.22

41

Nb92.91

42

Mo95.95

43

Tc(99)

44

Ru101.1

45

Rh102.9

46

Pd106.4

47

Ag107.88

48

Cd112.41

57†

La138.92

72

Hf178.50

73

Ta180.95

74

W183.86

75

Re186.22

76

Os190.2

77

Ir192.2

78

Pt195.09

79

Au197.0

80

Hg200.61

89††

Ac(227)

104

Rf(261)

105

Ha(262)

106

--(263)

59

Pr140.92

60

Nd144.27

61

Pm(145)

62

Sm150.35

63

Eu152.35

64

Gd157.26

91

Pa(231)

92

U238.07

93

Np(237)

94

Pu(242)

95

Am(243)

96

Cm(245)

65

Tb158.93

97

Bk(249)

66

Dy162.51

67

Ho164.94

68

Er167.2

69

Tm168.94

70

Yb173.04

71

Lu174.99

98

Cf(251)

99

Es(254)

100

Fm(255)

101

Md(256)

102

No(254)

103

Lr(257)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Mole of H2O = _____grams?

Molar Reflections*

Yesterday I took a drink of water And something strange happened in my head I made an actual connectionWith something that my chemistry teacher saidI could visualize lots and lots of moleculesMovin in the water to and fro…and then I thoughtIf I just drank 18 grams of waterI just drank a

Molar reflections, my mind is running freeMaking connections between the world and chemistryA mole is more than a number, more than just a wordIt’s an amount that’s equal to

*Mike Offutt©2002

6.02 times ten to the twenty third!

mole of H2O!

Moles and Solution Concentration

# M = # Molar Solution

# = moles per 1000 mL of solution or mmoles per mL of solution

Example:2.0 M NaCl contains 2 moles NaCl per 1000 mLor 2 mmoles per mL of solution

Salt solution preparation• Read the reagent label for the salt sample CuSO4• 5 H2O CuSO4

DEMO

= Hydrated copper sulfate

= anhydrous copper sufate

Salt solution preparation• Determine the mass of a mole of the salt CuSO4• 5 H2O

ExampleCuSO4· 5 H2O = Cu + S + 4 (O) + 5 (2 x H + O) = 63.55 + 32.07 + 4(16) + 5 (2 + 16) = 249.62

= Hydrated copper sulfate

Salt solution preparation• Determine the mass of salt needed to prepare

100 mL of 0.10 M solutionQ. How many grams of CuSO4·5H2O are needed?

249.62 g x 0.10 mol x 100 mL = 2.50 g1 mol 1000 mL

DEMO

Salt Solution preparation

Calibration line

Volumetric flasks

•Transfer the weighed sample(2.50 g of CuSO4·5H2O) to a 100mL Vol flask and add water to thecalibration line

Solution Preparation Salt solution preparation

Information: FW NaClNa + Cl = FW NaCl22.99 + 35.46 = 58.45 g NaCl

Your teammate adds 1 liter (1000 mL) of water to58.45 g of NaCl to prepare 1.0 M NaCl. Theresulting solution was too dilute ( < 1.0 M ). Why?

Answer: 1 mol NaCl was contained in a volumegreater than 1000 mL. Less than 1000 mL ofwater is required since the salt itself occupiesvolume.

Solution dilution

One buretcontains

water

Burets clamped to ring stand

One buretcontains thesolution tobe diluted

Solution Dilution

Add H2O

Solution Diluted solution

• Initial moles or mmoles = Final moles or mmoles

Dilution of Solutions

If V= milliliters: M x V = mmol x mL = mmol

mL

Initial mol or mmol = Final mol or mmol M1V1 = M2V2

If V= liters: M x V = mol x L = mol L

Solution Dilution

0.10 M x 10 mL →

+ 10 mL H2O

initial mmoles = final mmoles

Add H2O

1 mmol = 1 mmol

.05 M x 20 mL

Q. What volume of 0.10 M Ni(NO3)2 do you need toprepare 20.0 mL of 0.07 M Ni(NO3)2?

0.10 M • X mL = 0.07 M • 20.0 ml

M1V1 = M2V2

Q. What volume of H2O do you add to14.0 mL of 0.10 M Ni(NO3)2?

X = 14.0 mL Ni(NO3)2

6. 0 mL H2O

Solution Delivery

Fill the buret and tip Record the initial volume

Solution Delivery

Open the stopcock todeliver the solution intothe flask.

Record the final volume;Calculate and record thedelivered solution volume

Q. What volume of 0.20 M Ni(NO3)2 and water do youuse to prepare 10 mL of 0.16 M Ni(NO3)2?

0.20 M • X mL = 0.16 M • 10 ml

M1V1 = M2V2

8 mL 0.20 M Ni(NO3)2 + 2 mL H2O

Light source Diffractiongrating

Samplesolution

Detector

Use a spectrophotometer to examine the relationshipbetween solution color and absorption andtransmission of visible light.

Parts 2 and 3: Electrons and Solution Color Spectrophotometer

• Record visible wavelength colors (Part 2)

Spectrophotometer

• Record sample absorbance values across thevisible spectrum wavelengths (Part 3).

A plot of absorbance versus wavelength

Absorption Spectrum

Absorbance λmax

Light Absorbance vs. Transmission

0% 10% T 100%

∞ 2 1 A 0

• Absorbance values have no unitsAbs = 1 10% light transmitted

Abs = 2 1% light transmitted

ABSORBANCE = -LOG TRANSMITTANCE Q. Identify the wavelength of transmission max inthe absorption spectrum below.

Absorption Spectrum

Transmission λmax

Q. What factor is responsible for changes inabsorbance values?

Absorption Spectrum

Answer.The samplesabsorptivityfactor

Beer-Lambert Law A λ = ε c l

absorptivity factor • concentration • path length

Absorbance at λ =

• Concentration and path length are held constantwhile taking the sample’s spectrum (Part 3)

…. To be continued next pre-lab lecture