Can $\ce{NaOH}$ and $\ce{NaH2PO2}$ exist together in aqueous solution?

My textbook denies it, but I feel that since $\ce{NaH2PO2}$ is acidic, it should react with $\ce{NaOH}$, because in my textbook it is written that salts of even weak acids can react with a strong Base (e.g., $\ce{NaHCO3}$ is mentioned to react with $\ce{NaOH}$).

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    $\begingroup$ $\ce{NaH2PO2}$ is not acidic and it is a common catch for less observant students. ( Or rather has extremely low, not mentioned acidity.), as the remaining hydrogens of hypophosphorous acid are bound directly to phosphorus.( $\ce{HO-PH2=O}$ ). Similarly, only 2 of 3 hydrogen atoms of phosphorous acid $\ce{H3PO3}$ are acidic. $\endgroup$
    – Poutnik
    Commented Jun 23, 2020 at 13:38
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    $\begingroup$ Neither of substances really exists in aqueous solution. They're both fairly dissociated into ions. $\endgroup$
    – Zhe
    Commented Jun 23, 2020 at 16:09
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    $\begingroup$ Can you give the title of your textbook, and paraphrase a few lines? $\endgroup$
    – Karl
    Commented Jun 23, 2020 at 18:31
  • $\begingroup$ @Karl , Its the study material provided by my coaching classes for IIT JEE prep. You won't really need to know the name. $\endgroup$
    – Aryan Arya
    Commented Jun 25, 2020 at 17:13
  • $\begingroup$ Well, I can only advise you to take everything coming out of the IIT-JEE complex with the utmost caution. Just my opinion, based on the purely anecdotal evidence of questions I have seen here on chem.SE. $\endgroup$
    – Karl
    Commented Jun 26, 2020 at 19:29

1 Answer 1


Your question: Can $\ce{NaOH}$ and $\ce{NaH2PO2}$ exist together in aqueous solution?

I assume what you meant is your textbook is saying when two separate solutions of $\ce{NaOH}$ and $\ce{NaH2PO2}$ are combined, there should be no reaction. If that is what you meant "exist together," then your textbook is correct because there won't be an acid-base reaction since $\ce{NaH2PO2}$ has no "acidic hydrogen" contrast to $\ce{NaH2PO4}$ and $\ce{Na2HPO4}$ as Poutnik mentioned in his comment (more descriptive presentation would be $\ce{Na^+^-OP(=O)H2}$). The following diagram summerizes this point:

Phoshates and carbonates

As diagram shows $\ce{NaH2PO2}$ (sodium hypophosphite) does not have any acidic protons to react with strong bases like $\ce{NaOH}$. The two hydrogens in $\ce{NaH2PO2}$ have attach ed to phosphorous atom in covalent bonds. And also showing is sodium bicarbonate, which has one acidic proton to react with $\ce{NaOH}$.


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