DP Chemistry Questionbank

What is the charge on the iron(III) complex ion in [Fe(OH)₂(H₂O)₄]Br?

A.     0

B.     1+

C.     2+

D.     3+

Describe, in terms of the electrons involved, how the bond between a ligand and a central metal ion is formed.

Formulate an equation for the oxidation of nickel(II) sulfide to nickel(II) oxide.

The nickel obtained from another ore, nickeliferous limonite, is contaminated with iron. Both nickel and iron react with carbon monoxide gas to form gaseous complexes, tetracarbonylnickel, $\text{Ni(CO}{\text{)}}_{\text{4}}\text{(g)}$, and pentacarbonyliron, $\text{Fe(CO}{\text{)}}_{\text{5}}\text{(g)}$. Suggest why the nickel can be separated from the iron successfully using carbon monoxide.

Suggest why experiments involving tetracarbonylnickel are very hazardous.

Ammonia is a stronger ligand than water. Which is correct when concentrated aqueous ammonia solution is added to dilute aqueous copper(II) sulfate solution?

A.     The d-orbitals in the copper ion split.

B.     There is a smaller splitting of the d-orbitals.

C.     Ammonia replaces water as a ligand.

D.     The colour of the solution fades.

Explain why iron forms many different coloured complex ions.

Describe the bond formation when urea acts as a ligand in a transition metal complex ion.

Explain why transition metals exhibit variable oxidation states in contrast to alkali metals.

Which is correct for the complex ion in [Fe(H₂O)₅Cl]SO₄?

State and explain the magnetic property of iron(II) and iron(III) ions.

Predict two other chemical properties you would expect rhenium to have, given its position in the periodic table.

Which electrons are removed from iron (Z = 26) to form iron(II)?

A. two 3d electrons

B. two 4s electrons

C. one 4s electron and one 3d electron

D. two 4p electrons

What is the oxidation state of the metal ion and charge of the complex ion in [Co(NH₃)₄Cl₂]Cl?

Which of these statements are correct?

I. Zinc is not a transition element.
II. Ligands are Lewis bases.
III. Manganese(II) chloride is paramagnetic.

A.  I and II only

B.  I and III only

C.  II and III only

D.  I, II and III

What is the overall charge, $x$, of the chromium (III) complex?

$\left[\mathrm{Cr}\right({\mathrm{H}}_2\mathrm{O}{)}_4{\mathrm{Cl}}_2{]}^x$

A.  0

B.  1+

C.  2−

D.  3+

Which complex ion contains a central ion with an oxidation state of +3?

A.  [PtCl₆]²⁻

B.  [Cu(H₂O)₄(OH)₂]

C.  [Ni(NH₃)₄(H₂O)₂]²⁺

D.  [Co(NH₃)₄Cl₂]⁺

Mg(OH)⁺ is a complex ion, but Mg is not regarded as a transition metal. Contrast Mg with manganese, Mn, in terms of one characteristic chemical property of transition metals, other than complex ion formation.

What is the correct explanation for the colour of [Cu(H₂O)₆]²⁺?

A. Light is absorbed when an electron moves to a d orbital of higher energy.

B. Light is released when an electron moves to a d orbital of higher energy.

C. Light is absorbed when electrons move from the ligands to the central metal ion.

D. Light is absorbed when electrons move between d and s orbitals.

The oxidation state of cobalt in the complex ion [Co(NH₃)₅Br]^x is +3. Which of the following statements are correct?

I.   The overall charge, x, of the complex ion is 2+.
II.  The complex ion is octahedral.
III. The cobalt(III) ion has a half-filled d-subshell.

A.  I and II only

B.  I and III only

C.  II and III only

D.  I, II and III

Outline why transition metals form coloured compounds.

Explain why iron forms many different coloured complex ions.

[CoCl₆]^3– is orange while [Co(NH₃)₆]³⁺ is yellow. Which statement is correct?

A. [CoCl₆]^3– absorbs orange light.

B. The oxidation state of cobalt is different in each complex.

C. The different colours are due to the different charges on the complex.

D. The different ligands cause different splitting in the 3d orbitals.

Copper(II) ion solutions are blue. Suggest, giving your reason, a suitable wavelength of light for the analysis.

Explain why, when ligands bond to the iron ion causing the d-orbitals to split, the complex is coloured.

Identify the colour of the emission spectrum of lithium using section 17 of the data booklet.

Describe how the blue colour is produced in the Cu(II) solution. Refer to section 17 of the data booklet.

Deduce why the Cu(I) solution is colourless.

Examine the relationship between the Brønsted–Lowry and Lewis definitions of a base, referring to the ligands in the complex ion [CuCl₄]²⁻.

The electron configuration of copper makes it a useful metal.

Explain why a copper(II) solution is blue, using section 17 of the data booklet.

Deduce, giving a reason, which complex ion [Cr(CN)₆]³⁻ or [Cr(OH)₆]³⁻ absorbs higher energy light. Use section 15 of the data booklet.

[Cr(OH)₆]³⁻ forms a green solution. Estimate a wavelength of light absorbed by this complex, using section 17 of the data booklet.

Copper is a transition metal that forms different coloured complexes. A complex [Cu(H₂O)₆]²⁺(aq) changes colour when excess Cl⁻(aq) is added.

Explain the cause of this colour change, using sections 3 and 15 from the data booklet.

Why is hydrated copper (II) sulfate blue?

A.  Blue light is emitted when electrons return to lower d-orbitals.

B.  Light complimentary to blue is absorbed when electrons return to lower d-orbitals.

C.  Blue light is emitted when electrons are promoted between d-orbitals.

D.  Light complimentary to blue is absorbed when electrons are promoted between d-orbitals.

[Cr(OH₂)₆]³⁺ is violet and [Cr(NH₃)₆]³⁺ is yellow. What is correct?

The Colour Wheel

Mg(OH)⁺ is a complex ion, but Mg is not regarded as a transition metal. Contrast Mg with manganese, Mn, in terms of one characteristic chemical property of transition metals, other than complex ion formation.