Transition Metals Flashcards

What is the purpose of increasing the surface area of a solid catalyst?

Increasing the surface area improves the effectiveness of the catalyst by providing more active sites for reactant adsorption.
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What is the purpose of increasing the surface area of a solid catalyst?	Increasing the surface area improves the effectiveness of the catalyst by providing more active sites for reactant adsorption.
What factors affect the effectiveness of catalytic activity in heterogeneous catalysis?	The strength of adsorption and the surface area of the catalyst are important factors in determining the effectiveness of catalytic activity.
How does heterogeneous catalysis work?	Heterogeneous catalysis involves the adsorption of reactants at active sites on the surface of a solid catalyst, leading to catalytic action.
What is the difference between a heterogeneous and homogeneous catalyst?	A heterogeneous catalyst is in a different phase from the reactants, while a homogeneous catalyst is in the same phase.
Describe the role of catalysts in reactions.	Catalysts provide an alternative route with a lower activation energy, allowing reactions to occur more quickly.
What is catalysis?	Catalysis is process of increasing reaction rates without being consumed.
Name a transition metal commonly used as a catalyst.	Platinum (Pt) and nickel (Ni) are commonly used as catalysts in heterogeneous catalysis.
Describe the steps involved in a manganate titration.	The steps involved in a manganate titration include finding the moles of KMnO4, finding the moles of Fe2+ in the solution, calculating the percentage of iron by mass, and finding the mass of Fe in the solution.
What happens when zinc is added to vanadium in acidic solution?	Zinc can reduce the vanadium down through each successive oxidation state, causing the color to change from yellow to blue to green to violet.
What is the influence of pH and ligands on the redox potential of a transition metal ion changing from a higher to a lower oxidation state?	The redox potential is influenced by pH and the ligand. Compounds with high oxidation states tend to be oxidizing agents.
What are the general trends in the relative stability of +2 and +3 oxidation states across the period?	The relative stability of the +2 oxidation state with respect to the +3 oxidation state increases across the period.
Describe variable oxidation states of transition metals.	Transition metals can form ions with different oxidation states. They lose the 4s electrons before the 3d electrons.
What is the relationship between the amount of light absorbed and the concentration of the absorbing species in spectrophotometry?	The amount of light absorbed is proportional to the concentration of the absorbing species.
How does the addition of cobalt affect the redox equations in the catalysed reaction?	The addition of cobalt results in two new redox equations, where Co2+ is oxidized to Co3+ and Co3+ is reduced to Co2+.
How does silver iodide react with ammonia?	Silver iodide does not react with ammonia, it is insoluble.
Describe the reaction between silver bromide and concentrated ammonia.	Silver bromide dissolves to form a complex ion [Ag(NH3)2]+.
What is the purpose of Tollens' reagent?	Tollens' reagent is used to distinguish between aldehydes and ketones.
What happens when silver chloride is dissolved in dilute ammonia?	Silver chloride dissolves to form [Ag(NH3)2]+ complex ion.
Define a transition metal.	A transition metal is an element that has a partially filled d subshell.
How does silver differ from transition metals in terms of colored compounds?	Silver does not form colored compounds.
What is the oxidation state of silver in its complexes?	Silver complexes have a +1 oxidation state.
Describe the color of silver complexes.	All silver complexes are colorless solutions.
Do the two mechanism equations involving cobalt ions add up to the original full non-catalysed equation?	Yes, the two mechanism equations involving cobalt ions add up to the original full non-catalysed equation.
Why do compounds like Zn2+ and Cu+ ions not exhibit colour?	These ions have a full d shell (e.g., 3d10), so there is no space for electrons to transfer and no energy transfer equal to that of visible light.
Define a catalysed reaction.	A catalysed reaction is a chemical reaction that is facilitated by the presence of a catalyst, which increases the rate of the reaction without being consumed in the process.
How can electrode potentials be used to determine if a substance can act as a homogeneous catalyst?	For a substance to act as a homogeneous catalyst, its electrode potential must lie between the electrode potentials of the two reactants. It will first reduce the reactant with the more positive electrode potential and then oxidize the reactant with the more negative electrode potential.
What is autocatalysis? Provide an example involving the reaction between ethanedioate and manganate ions.	Autocatalysis is a process where one of the products of a reaction acts as a catalyst for the same reaction. An example is the autocatalytic reaction between ethanedioate (C2O4 2-) and manganate ions (MnO4-), where the Mn2+ ions produced act as a catalyst for the reaction.
Describe an example of homogeneous catalysis involving the reaction between iodide and persulfate ions.	The uncatalyzed reaction between iodide and persulfate ions is slow because it requires a collision between two negative ions, which are repelled by each other. The catalyzed reaction, using Fe2+ ions, proceeds through an alternative route with lower activation energy, resulting in the formation of sulfate ions.
What is the role of transition metals in homogeneous catalysis?	Transition metals can act as homogeneous catalysts because they can form various oxidation states. They are able to donate and receive electrons, as well as oxidize and reduce. This is due to the partially filled sub-shells of d electrons in transition metal ions, which can easily lose or gain electrons.
Describe homogeneous catalysis.	Homogeneous catalysis occurs when catalysts and reactants are in the same phase, and the reaction proceeds through an intermediate species with a different oxidation state than the original transition metal. At the end of the reaction, the original oxidation state will reoccur, illustrating the importance of variable oxidation states of transition metals in catalysis.
What happens when high concentration of chloride ions is added to an aqueous ion of Cu?	The coordination number of Cu changes from 6 to 4, resulting in the formation of [CuCl4]2- and a change in color to yellow/green.
Why is CO toxic to humans?	CO can form a strong coordinate bond with haemoglobin, replacing oxygen and attaching to the haemoglobin.
What is the role of oxygen in haemoglobin?	Oxygen forms a coordinate bond to Fe(II) in haemoglobin, enabling oxygen to be transported in the blood.
Describe multidentate ligands.	Multidentate ligands can form multiple coordinate bonds per ligand.
Define octahedral shape in relation to bidentate ligands.	Octahedral shape refers to a complex with bidentate ligands, where each ligand bonds twice to the metal ion and the bond angles are 90°.
What is the coordination number of a complex with bidentate ligands?	A complex with bidentate ligands has a coordination number of 6.
Describe bidentate ligands.	Bidentate ligands have two atoms with lone pairs and can form two coordinate bonds per ligand.
What is the shape of [CoCl4]2-?	[CoCl4]2- has a tetrahedral shape.
What is the chelate effect?	The chelate effect refers to the increased stability of a complex when a monodentate ligand is substituted with a bidentate or multidentate ligand.
What is the difference between monodentate, bidentate, and multidentate ligands?	Monodentate ligands can form one coordinate bond per ligand, bidentate ligands can form two coordinate bonds per ligand, and multidentate ligands can form six coordinate bonds per ligand.
What is the coordination number?	The coordination number is the number of coordinate bonds formed to a central metal ion.
Describe substitution reactions in transition metal complexes.	Substitution reactions involve the exchange of ligands in a complex without a change in the coordination number of the central metal ion.
How is co-ordinate bonding involved in complex formation?	Co-ordinate bonding occurs when the shared pair of electrons in the covalent bond come from only one of the bonding atoms.
What is a ligand?	A ligand is an atom, ion, or molecule that can donate a lone electron pair to form a coordinate bond with a central metal ion.
Define complex formation.	Complex formation refers to the formation of a central metal ion surrounded by ligands.
Describe optical isomerism in complex ions.	Optical isomerism occurs when a complex has non-superimposable mirror images due to the presence of chiral ligands.
Describe how changing a ligand or coordination number can affect the colour of a complex ion.	Changing a ligand or coordination number alters the energy split between the d orbitals, changing the frequency of light absorbed.
What happens when visible light is passed through a sample of a coloured complex ion?	Some of the light is absorbed by the coloured complex ion.
Define spectrophotometry.	Spectrophotometry is a method that uses the absorption of visible light to determine the concentration of coloured ions.
How does colour arise in coloured ions?	Colour arises from electronic transitions between different d orbitals, from the ground state to excited states.
What is the role of ligands in the formation of coloured ions?	Ligands cause the 5 d orbitals in an octahedral complex ion to split into two energy levels.
Describe the factors that can cause colour changes in ions.	Colour changes arise from changes in oxidation state, co-ordination number, and ligand.
Define E-Z isomerism in complex ions.	E-Z isomerism refers to the different spatial arrangements of ligands around a central metal atom in a complex, where ligands are prioritized based on the Cahn-Ingold-Prelog priority rules.
Do larger ligands tend to form complexes with transition metal ions?	Yes, larger ligands tend to form complexes with transition metal ions.
What is an example of a complex that exhibits cis-trans isomerism?	An example of a complex with cis-trans isomerism is trans-Ni(NH3)2Cl2 and cis-Ni(NH3)2Cl2.
Describe the general properties of transition metals.	Transition metals have variable oxidation states, form colored ions, exhibit catalytic activity, and have complex formation abilities.
How can square planar complexes exhibit cis-trans isomerism?	Square planar complexes can exhibit cis-trans isomerism when two different ligands occupy adjacent positions.
Define cis-trans isomerism in complex ions.	Cis-trans isomerism refers to the different spatial arrangements of ligands around a central metal atom in a complex.
What is the common shape for transition metal ions?	Transition metal ions commonly form octahedral complexes.
Describe the shapes of complex ions.	Complex ions can have various shapes, such as square planar, octahedral, tetrahedral, and linear.
What is the 1:1 ratio in EDTA titrations?	In EDTA titrations, there is always a 1:1 ratio between the metal ion and the EDTA complex formed.
Explain the process of EDTA titrations.	EDTA titrations involve the formation of stable EDTA complexes with metal ions, which can be quantitatively determined using a suitable indicator.
How does the stability of EDTA complexes have practical applications?	EDTA complexes can be used to remove poisonous heavy metal ions from rivers and to remove calcium ions from hard water in shampoos.
Describe the entropy change in reactions involving the chelate effect.	Reactions involving the chelate effect have a positive entropy change because there are more molecules of products than reactants, leading to increased disorder.
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