Inorganic chemistry：練習問題

What is the characteristic flame color observed when a sample containing sodium ions, \(Na^+\), is heated in a Bunsen burner flame?

A student adds a piece of zinc metal to an aqueous solution of copper(II) sulfate. Which observation would provide evidence that a displacement reaction has occurred?

In an experiment to determine the percentage of oxygen in the air, 100 \(cm^3\) of air is passed back and forth over excess heated copper turnings in a closed system. After the volume of gas stops decreasing and the apparatus has cooled, the final volume of gas is 79 \(cm^3\). What is the percentage of oxygen in the sample?

A student is preparing a pure, dry sample of soluble copper(II) sulfate by reacting excess copper(II) oxide with dilute sulfuric acid. Why is it necessary to add the copper(II) oxide in excess?

A green solid, X, produces a blue-green flame and reacts with dilute hydrochloric acid to release a gas that turns limewater cloudy. Identify X and describe how to prepare pure, dry crystals of copper(II) nitrate from X, naming the acid used and explaining the importance of adding X in excess.

A student investigates the reactivity of different metals and the prevention of corrosion.

(a) The student adds a piece of zinc to a solution of iron(II) sulfate (\(FeSO_4\)). A displacement reaction occurs.
(i) Write the ionic equation for this reaction, including state symbols.
(ii) Identify the substance that is oxidised in this reaction and explain your choice in terms of electron transfer.

(b) Iron rusts when left in certain conditions.
(i) State the two substances that must be present for iron to rust.
(ii) To prevent a large iron structure from rusting, a block of magnesium can be attached to it. Name this specific method of protection and explain, in terms of reactivity, why this prevents the iron from rusting.