Question

Complete the following reaction, ${P_4} + NaOH + {H_2}O \to ?$
A) $P{H_3} + N{a_2}HP{O_4}$
B) $P{H_3} + Na{H_2}P{O_2}$
C) ${H_3}P{O_4} + NaO$
D) $P{H_3} + N{a_2}P{O_4}$

Answer 1

Analyze the reaction and the products given in the options. One can also try to relate the products in the reaction and try to balance the equation with the given products and make the correct choice.

Complete step by step answer:

1. First of all we will try to write the reaction equation which will give us an idea about the reaction products as below,
   ${P_4} + NaOH + {H_2}O\xrightarrow{{Heat}}P{H_3} + Na{H_2}P{O_2}$
   In the above reaction when phosphorus reacts with the sodium hydroxide and water in presence of heat we get the products as phosphine and sodium hypophosphite.
2. The above reaction is not balanced and the new balanced equation will be as follows,
   Balanced chemical reaction:
   ${P_4} + 3NaOH + 3{H_2}O\xrightarrow{{Heat}}P{H_3} + 3Na{H_2}P{O_2}$
   Therefore, the products formed in the above reaction are $P{H_3} + Na{H_2}P{O_2}$ which shows option B as the correct choice of answer.

Additional information: The phosphine molecule i.e. $P{H_3}$ formed in the above reaction is a colorless gas and has flammable properties. The phosphine molecule is classed as pnictogen hydride which are binary compounds of hydrogen where phosphorus is covalently bonded to the hydrogen atom. The phosphine molecule shows geometry the same as the ammonia molecule. The sodium hypophosphite is a monohydrate sodium salt of hypophosphorous acid. It is solid at room temperature and appears as a white crystal that is odorless.

Note:
In the above reaction, phosphine is the main product and the sodium salt of hypophosphorous acid is the subsidiary product. The phosphine is used for the phytosanitary treatment of grain seeds, dry fruits, plant products, and dates. It also has main use in the semiconductor industry as an introduction material of phosphorus into the crystals of silicon.