Discussion Forum

The reaction of white phosphorus with aqueous NaOH gives phosphine along with another phosphorous containing compound. The reaction type; the oxidation  states of phosphrous in phosphine and the other product are respectively.

Answer:

Explanation:

The reaction of white phosphorus with aqueous alkali is

 $P_{4}+3NaOH+3H_{2}O \rightarrow  PH_{3}+NaH_{2}PO_{2}$

In the above reaction phosphorus is simultaneously oxidized

$[P_{4}(O) \rightarrow NaH_{2} P^{+1}O_{2}]$  as well as reduced  [$P_{4}(0) \rightarrow PH_{3}]$ 

Therefore, this is an example of disproportionation reaction. Oxidation number of phosphorus in $PH_{3}$ is -3 and in $NaH_{2}PO_{2}$ is +1.

However,+1 oxidation no. is not given in any option, one might think that $NaH_{2}PO_{2}$, has gone to further decomposition on heating.

 $2NaH_{2}PO_{2}$ $\underrightarrow{\triangle} Na_{2}H^{+5}PO_{4}+PH_{3}$