Question

What is the product formed when zinc reacts with strong $NaOH$?
A.Zinc oxide
B.Zinc hydroxide
C.Sodium Zincate
D.None of the above

Answer 1

To answer this question, you should recall the process of reaction of transition metals with NaOH. Most metals do not react with strong bases. However, zinc is an exception to this property of metals. It forms an oxide along with sodium.

Complete Step by step solution:
Zinc is atmospheric and hence it reacts with both acids and bases. Zinc reacts with $NaOH$ in aqueous medium to produce sodium zincate. The reaction can be represented as:
$2Na\left( {OH} \right) + ZnO{\text{ }} \to {\text{ }}N{a_2}Zn{O_2}{\text{ }} + {H_2}O$.
$N{a_2}Zn{O_2}$ is sodium zincate. An easy way to remember it is it is the sum of the molecular formula of sodium oxide and zinc oxide; however, it is not formed by the reaction of the two.
This compound is possible because $Zn$ is capable of displacing Hydrogen from both acids and bases and therefore is called an amphoteric metal and its oxide is an amphoteric oxide.

Hence, the correct answer is option C.

Additional information:
The different types of salts resulting from neutralization reaction are based on their constituents
1. Acidic salt: The salt resulting from partial neutralization of a polyprotic acid is known as an acidic salt. These salts have ionizable ${H^ + }$ ions along with another cation. Examples of this type of salt are etc.
2. Basic or Alkali Salt: This type of salt is formed by the partial neutralization of a strong base by a weak acid is known as a basic salt. These salts hydrolysis to form a basic solution. Example of this type of salts is: White lead $(2PbC{O_3}.Pb{\left( {OH} \right)_2}).$
3. Double salt: These types of salts contain more than one cation or anion is known as double salt. They are obtained by the combination of two different salts crystallized in the same ionic lattice. Example of this type of salts is: Potassium sodium tartrate $(KNa{C_4}{H_4}{O_6}.4{H_2}O)$ which is also known as Rochelle salt.
4. Mixed Salts: These types of salts are made up of a fixed proportion of two salts, often sharing either a common cation or common anion is known as mixed salt.

Note: Even Aluminum is an amphoteric metal and its oxide is an amphoteric oxide. No other metals and their oxides can displace Hydrogen from bases.
The reactions that represent the amphoteric nature of aluminum are:
$2Al + 6HCl \to 2A{l^{3 + }} + 6C{l^ - } + 3{H_2}$
$2Al + 2NaOH + 6{H_2}O \to 2Na{[Al{(OH)_4}]^ - } + 3{H_2}$