Transition elements：練習題

Which is a characteristic physical property of transition elements?

Transition elements are often defined by their ability to form ions with variable oxidation numbers.
Which of the following describes the oxidation states of iron in the compounds \( \text{Fe}_2\text{O}_3 \) and \( \text{FeO} \)?

In the oxidation of sulfur dioxide to sulfur trioxide during the Contact process, a transition metal oxide is used as a catalyst.
What is the formula of this catalyst and what is the oxidation state of the transition metal within it?

A transition metal X forms an oxide with the formula \( X_{2}O_{3} \). If the oxidation state of oxygen is \(-2\), what is the oxidation number of X in this compound and what is a likely physical property of the compound?

In the identification of anions, acidified potassium manganate(VII) is used to test for the sulfite ion, \( \text{SO}_3^{2-} \).
What is the oxidation state change of the manganese during a positive test result?

State two physical properties of transition elements that distinguish them from the alkali metals in Group I.

A student has two unlabeled bottles containing aqueous solutions of transition metal ions. One contains iron(II) and the other contains iron(III).

Describe the observation when aqueous sodium hydroxide is added to each bottle to distinguish between the two ions.

Transition metals often act as catalysts due to their ability to exist in different oxidation states.

(a) Name the transition metal catalyst used in the hydrogenation of alkenes.
(b) Explain why a catalyst is preferred in industrial processes in terms of activation energy and rate of reaction.

Transition elements possess properties that distinguish them from the main-group metals like those in Group I.

(a) State two physical properties of transition elements that are different from those of Group I metals.
(b) Transition elements often form colored compounds. State the color of:
i. Copper(II) sulfate
ii. Iron(II) hydroxide
(c) Transition elements or their compounds are frequently used as catalysts. Name one transition element catalyst and the industrial process it is used in.

Transition metals are often compared to the alkali metals of Group I to highlight their unique characteristics.

(a) Compare transition metals to Group I metals in terms of:
i. Reactivity with cold water.
ii. Relative hardness.
(b) Manganese is a typical transition element. It forms a compound called potassium manganate(VII), \(KMnO_4\).
i. Define the term oxidising agent.
ii. Describe the colour change observed when acidified aqueous potassium manganate(VII) reacts with a reducing agent such as iron(II) ions.
(c) Transition elements often act as catalysts. Explain why using a catalyst is advantageous in large-scale industrial manufacture, referring to both rate of reaction and economic factors.