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CHEM 112
Homework
2015-2016
Week 13 Transition metals
Q UEST IO N 1
a. Write the electron configurations for the following atoms: Fe,
abbreviation.
Co,
Ni,
Ti. You can use the inert gas core
b. Write the election configurations for the +2 ions for each of these atoms.
Q UEST IO N 2
What is the electron configuration of the following transition metal ions? How many unpaired electrons are in each of these?
a.
b.
c.
d.
Z n2+
Co 3+
Mo 3+
Cu 2 +
Q UEST IO N 3
What is the electron configuration of the following transition metal ions? How many unpaired electrons are in each of these?
a.
b.
c.
d.
Pd 2 +
Au 3+
Ti 4 +
Fe 3+
Q UEST IO N 4
For the elements scandium through manganese, what is the highest oxidation state equal to?
A.
B.
C.
D.
E.
the number of 3d electrons
the principal quantum number of the period
the total number of 4s and 3d electrons
the total number of 4s, 3p, and 3d electrons
none of the above
Q UEST IO N 5
Find the coordination number of the metal, the charge of the complex, and the oxidation state of the transition metal ion for
the following complexes.
a. Na[Co(NH3) 2 Br 4 ]
b. [Fe(CN) 6 ]3−
c. K 2 [Ni(F 4 )]
d. [Cu(NH3) 4 ]Cl 2
e. [Cr(OH) 4 ]−
Q UEST IO N 6
What is the coordination number of the metal, the charge of the complex ion, and the oxidation state of the transition metal
for the following complexes?
a. Na[Co(EDTA)]
b. K 2 [Cd(C2 O 4 ) 2 ]
c. Pt(en)Cl 2
d. [Fe(porphine)]+
e. Na[Cr(CO 3) 2 (NH3) 2 ]
Copyright 2011-2016, PSU Chemistry All rights reserved
CHEM 112
Homework
Q UEST IO N 7
Which of the following statements is false?
A.
B.
C.
D.
E.
When transition metals are oxidiz ed, they lose s electrons before losing d electrons.
Many transition metals have more than one oxidation state.
Octahedral transition metal complexes can consist of a metal ion surrounded by three bidentate ligands.
Transition metal complexes are Lewis acid- base adducts.
A total of four ions are formed when [Co(NH3) 5 Br]Br 2 is dissolved in water.
Q UEST IO N 8
Which of the following substances has a central transition metal that has five electrons in a d subshell?
A. V atom
B. [Fe(CN) 6 ]3−
C. [Fe(CN) 6 ]4 −
D. MnO 2
E. [Fe(NH3) 6 ]2 +
Q UEST IO N 9
Which of the following species is LEAST likely to act as a ligand in a transition metal complex?
A. C2 O 4 2 −
B. F −
C. CH4
D. NH3
E. H2 O
Q UEST IO N 10
Which one of the following aqueous solutions will have the same concentration of ions as a 0.1 M solution of MgCl 2 ?
A. 0.1 M [Fe(H2 O) 6 ]Cl 3
B. 0.1 M K 3[Co(CN) 6 ]
C. 0.1 M Na 3[CoBr 6 ]
D. 0.1 M Na 4 [CoF 6 ]
E. 0.1 M [Ni(NH3) 4 ]Br 2
Q UEST IO N 11
Which of the following reactions will have a formation constant (K f ) with the largest value?
2+
2+
A. [Co(H2 O) 6 ] (aq) + 6 L(aq) → [Co(L) 6 ] (aq) + 6 H2 O(ℓ)
2+
2+
B. [Co(H2 O) 6 ] (aq) + 6 L(aq) → [Co(L) 6 ] (aq) + 6 H2 O(ℓ)
2+
2+
C. [Co(H2 O) 6 ] (aq) + 6 L(aq) → [Co(L) 6 ] (aq) + 6 H2 O(ℓ)
where L = NH3
where L =
where L =
2+
2+
D. Co(H2 O) 6 ] (aq) + 3 L(aq) → [Co(L) 3] (aq) + 6 H2 O(ℓ)
where L =
2+
2+
E. Co(H2 O) 6 ] (aq) + 2 L(aq) → [Co(L) 2 ] (aq) + 6 H2 O(ℓ)
where L =
Copyright 2011-2016, PSU Chemistry All rights reserved
2015-2016
CHEM 112
Homework
2015-2016
Q UEST IO N 12
Calculate the concentration of free Cu 2 +(aq) in 1 L of a solution that contains a total of 1 × 10 −3 mol of Cu(II) ion (free ions +
complexed ions) and that is 0.10 M in NH3 at equilibrium. (K f [Cu(NH3) 4 2 +] = 5 × 10 1 2 )
A.
B.
C.
D.
E.
1 × 10 −3 M
5 × 10 5 M
2 × 10 1 8 M
2 × 10 −1 2 M
2 × 10 −1 5 M
Q UEST IO N 13
What is the [Cr +3] in equilibrium with Cr(OH) 4 − (aq) when 0.010 mol of Cr(NO 3) 3 is dissolved in a liter of solution buffered at a
pH of 7.3? (K f for Cr(OH) 4 − is 8.0 × 10 2 9 )
A. 1.98 × 10 −3 M
B. 7.88 × 10 −6 M
C. 3.05 × 10 −8 M
D. 1.60 × 10 2 3 M
E. 2.00 × 10 −7 M
Q UEST IO N 14
Given that K s p for AgI = 8.3 × 10 −1 7 and K f for Ag(CN) 2 − (aq) = 1.0 × 10 2 1 , what is the equilibrium constant for the following
reaction? AgI(s) +2CN− (aq) ⇌ Ag(CN) 2 − (aq) + I− (aq)
A.
B.
C.
D.
E.
8.3 × 10 4
1.2 × 10 −5
1.0 × 10 −2 1
8.3 × 10 −1 7
1.2 × 10 1 6
Q UEST IO N 15
Which statement is true about a substance with unpaired electrons?
A.
B.
C.
D.
E.
It will
It will
It will
It will
It will
be
be
be
be
be
slightly attracted to a magnet.
slightly repelled by a magnet.
permanently magnetic.
brightly colored.
nonmetallic.
Q UEST IO N 16
Which one of the following complex ions will be paramagnetic?
A. [Fe(H2 O) 6 ]2 +(low spin)
B. [Fe(H2 O) 6 ]3+(low spin)
C. [Co(H2 O) 6 ]3+(low spin)
D. [Z n(H2 O) 4 ]2 +
E. [Cu(H2 O) 4 ]+
Copyright 2011-2016, PSU Chemistry All rights reserved
CHEM 112
Homework
2015-2016
Q UEST IO N 17
Which of the following transition metal complexes will be attracted to a magnetic field?
A. [Z n(H2 O) 6 ]2 + (weak ligand field)
B. [Mn(H2 O) 6 ]2 + (weak ligand field)
C. [TiCl 4 ] (weak ligand field)
D. [Ru(NH3) 6 ]2 + (strong ligand field)
E. [Ag(NH3) 4 ]+ (strong ligand field)
Q UEST IO N 18
Which one of the following compounds would interact with a magnetic field?
A. [Z n(NH3) 4 ]Cl 2
B. CaSO 4
C. [Cu(H2 O) 4 ]Br
D. [Co(en) 3]Cl 3 (low spin)
E. K[FeCl 4 ]
Q UEST IO N 19
a. A transition metal ion complex absorbs blue light of 450 nm. What color is the solution of this complex?
b. A transition metal ion complex absorbs yellow light of 565 nm. What color is the solution of this complex?
c. A transition metal ion complex absorbs red light of 670 nm. What color is the solution of this complex?
Q UEST IO N 20
Which one of the following compounds is likely to be colorless?
A. [Z n(OH2 ) 6 ]2 +
B. [Cu(OH2 ) 6 ]2 +
C. [Fe(OH2 ) 6 ]2 +
D. [Cr(OH2 ) 6 ]2 +
E. [Ni(OH2 ) 6 ]2 +
Q UEST IO N 21
The absorption of three solutions of transition metal ion complexes is measured. The results are given below. Which solution
has the largest crystal field splitting? Which one has the smallest?
I. absorption = 720 nm
II. absorption = 500 nm
III. absorption = 615 nm
Q UEST IO N 22
The colors of three aqueous solutions of transition metal complexes are given below. Which solution is expected to have the
largest crystal field splitting? Which one has the smallest?
I. blue
II. green
III. yellow
Copyright 2011-2016, PSU Chemistry All rights reserved
CHEM 112
Homework
2015-2016
Q UEST IO N 23
a. If an octahedral transition metal complex with a d 2 electron configuration absorbs light of wavelength equal to 650 nm,
what is the magnitude of the crystal field splitting parameter, Δo ?
b. What is the energy in kJ/mol?
Q UEST IO N 24
The crystal field splitting energy for a complex is 160 kJ/mol. What wavelength of light does this complex ab so rb ?
A.
B.
C.
D.
E.
750 nm (red light)
550 nm (green light)
124 nm (ultraviolet light)
400 nm (blue light)
600 nm (orange light)
Q UEST IO N 25
For the octahedral complexes below determine the following:
I. How many d electrons are associated with the central metal ion?
II. Draw the energy level diagram of the crystal field.
III. Determine the number of unpaired electrons in each complex.
a. [FeCl 6 ]3− (high spin)
b. [Fe(NO 2 ) 6 ] 3− (low spin)
c. Mo(NH3) 6 ]2 + (high spin)
Q UEST IO N 26
Cr(OH2 ) 6 3+ is violet, while another monodentate ligand, L, produces a green CrL6 3+ complex. Which of the following
statements is incorrect?
A. The octahedral crystal field splitting Δo is smaller for CrL6 3+ than it is for Cr(OH2 ) 6 3+.
B. Cr(OH2 ) 6 3+ absorbs violet light.
C. Cr(OH2 ) 6 3+ has three unpaired electrons.
D. CrL6 3+ has three unpaired electrons.
E. The position of H2 O in the spectrochemical series is higher (stronger field) than the position of L (weaker field).
Copyright 2011-2016, PSU Chemistry All rights reserved