Question

Unlike other Group \(2 \mathrm{~A}(2)\) metals, beryllium reacts like aluminum and zinc with concentrated aqueous base to release hydrogen gas and form oxoanions of formula \(\mathrm{M}(\mathrm{OH})_{4}^{n-}\). Write equations for the reactions of these three metals with \(\mathrm{NaOH}\).

Short answer

The reactions are summarized as follows: \[ \text{Be} + 2 \text{NaOH} + 2 \text{H}_2\text{O} \rightarrow \text{Na}_2[\text{Be}(\text{OH})_4] + \text{H}_2 \] \[ 2\text{Al} + 2 \text{NaOH} + 6 \text{H}_2\text{O} \rightarrow 2\text{Na}[\text{Al}(\text{OH})_4] + 3 \text{H}_2 \] \[ \text{Zn} + 2 \text{NaOH} + 2 \text{H}_2\text{O} \rightarrow \text{Na}_2[\text{Zn}(\text{OH})_4] + \text{H}_2 \]

Step-by-step solution

Identify the General Form of Reaction

Beryllium, aluminum, and zinc react with concentrated aqueous base (NaOH) to release hydrogen gas and form oxoanions \( M(OH)_4^{n-} \) where M represents the metal. The general form of the reaction for metals reacting with a base is: \[ M + \text{NaOH} + \text{H}_2\text{O} \rightarrow M(\text{OH})_4^{n-} + \text{H}_2 \]

Write the Equation for Beryllium

For beryllium, \( \text{Be} \), the reaction with NaOH and water can be written as follows: \[ \text{Be} + 2 \text{NaOH} + 2 \text{H}_2\text{O} \rightarrow \text{Na}_2[\text{Be}(\text{OH})_4] + \text{H}_2 \]

Write the Equation for Aluminum

For aluminum, \( \text{Al} \), the reaction with NaOH and water is: \[ 2\text{Al} + 2 \text{NaOH} + 6 \text{H}_2\text{O} \rightarrow 2\text{Na}[\text{Al}(\text{OH})_4] + 3 \text{H}_2 \]

Write the Equation for Zinc

For zinc, \( \text{Zn} \), the reaction with NaOH and water is written as follows: \[ \text{Zn} + 2 \text{NaOH} + 2 \text{H}_2\text{O} \rightarrow \text{Na}_2[\text{Zn}(\text{OH})_4] + \text{H}_2 \]

Key concepts

Beryllium reactions

Beryllium is a unique element in Group 2A because of its small size and high ionization energy. Unlike other alkali earth metals, beryllium reacts with a concentrated aqueous base like NaOH to release hydrogen gas and form a complex ion known as a hydroxoberyllate ion. This behavior is similar to certain properties observed in aluminum.
The chemical equation for this reaction is: \[ \text{Be} + 2 \text{NaOH} + 2 \text{H}_2\text{O} \rightarrow \text{Na}_2[\text{Be}(\text{OH})_4] + \text{H}_2 \] Here, beryllium reacts with sodium hydroxide and water to produce sodium tetrahydroxoberyllate and hydrogen gas.
Note the formation of the complex ion \[ \text{Be}(\text{OH})_4^{2-} \]. This is key to understanding beryllium's unique chemistry with bases.

Aluminum reactions

Aluminum is a metal that, when reacting with a concentrated aqueous base such as NaOH, also forms a complex ion. This reaction showcases similarities in behavior with beryllium and zinc. The reaction with NaOH is: \[ 2\text{Al} + 2 \text{NaOH} + 6 \text{H}_2\text{O} \rightarrow 2\text{Na}[\text{Al}(\text{OH})_4] + 3 \text{H}_2 \] Here, aluminum reacts with sodium hydroxide and water to produce sodium tetrahydroxoaluminate and hydrogen gas.
The complex ion formed in this reaction is \[ \text{Al}(\text{OH})_4^- \]. This reaction not only demonstrates aluminum's amphoteric nature but also its ability to form hydroxide complexes similar to beryllium.

Zinc reactions

Zinc's behavior in reaction with concentrated NaOH is similar to that of beryllium and aluminum, forming a complex ion. This property makes zinc an interesting study in comparison with other transition metals and Group 2A metals. The reaction equation is: \[ \text{Zn} + 2 \text{NaOH} + 2 \text{H}_2\text{O} \rightarrow \text{Na}_2[\text{Zn}(\text{OH})_4] + \text{H}_2 \] Zinc reacts with sodium hydroxide and water to form sodium tetrahydroxozincate and hydrogen gas.
The complex ion \[ \text{Zn}(\text{OH})_4^{2-} \] formed in the reaction highlights zinc's similarity with beryllium and aluminum in their reactions with NaOH.