Question

The reaction between sodium and water can be made less vigorous by:
A.lowering the temperature
B. adding a little alcohol
C. amalgamating sodium
D. adding a little acetic acid

Answer 1

The mechanism by which reaction is made less vigorous is by adding a thin layer at the surface of contact of both sodium and water, so that the reaction proceeds very slowly. Limited amount of sodium is made to react with a limited amount of water.

Complete step by step solution:
In order to answer the following question, we need to learn about the properties of sodium. Sodium is a very reactive metal present group 1 in the periodic table. It has an atomic mass of 23 and is very soft and silvery white in nature. It has only one stable isotope and is an alkali metal. Since sodium is very reactive in nature, it is generally not found in the free state, rather it is prepared from compounds or minerals like feldspar, sodalite as well as rock salt or NaCl. Sodium has one electron extra from neon, counting to 11 electrons. Since one electron is extra to attain noble gas configuration, sodium tries to get rid of this electron, and that is the reason sodium is the most reactive. This also accounts for the high reduction potential for sodium, as the reduction potential for the $N{{a}^{+}}/Na$ couple is -2.7 volts. Now let us come to the question. Sodium is a very reactive metal and it does react vigorously with water to form sodium hydroxide solution NaOH.
$Na+{{H}_{2}}O\to NaOH+{{H}_{2}}+\Delta$
A lot of heat is generated in this reaction. However, if we cut off the contact of sodium from the water surface, then the reaction wont take place. Now this can be achieved by adding amalgamating sodium. It contains mercury amalgam and it does not react with sodium, it forms a layer and cuts off contact of sodium and water.

So, our correct answer is option C.

NOTE: Sodium is so reactive that it may even react with the oxygen present in the air. That is why sodium metal is never kept in the open, rather it is kept in sealed bottles, filled with kerosene. Kerosene does the same job as amalgamating sodium.