Select from the response list the compound or ion that best fits the description: conjugate base of [tex]$H _3 PO _4$[/tex].
[tex]$PO _4^{3-}$[/tex]
[tex]$HPO _4{ }^{2-}$[/tex]
[tex]$H _3 PO _4$[/tex]
[tex]$H _2 PO _4^{-}$[/tex]
Answer (2)
The conjugate base of H 3 P O 4 is formed by removing one proton, resulting in H 2 P O 4 − . This adjustment leads to a negative charge due to the loss of the H + ion. Therefore, the correct answer is H 2 P O 4 − .
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Identify that the conjugate base is formed by removing a proton ( H + ) from the acid.
Remove one proton from H 3 P O 4 to obtain H 2 P O 4 .
Adjust the charge accordingly, resulting in H 2 P O 4 − .
The conjugate base of H 3 P O 4 is H 2 P O 4 − .
Explanation
Understanding Conjugate Bases The problem asks us to identify the conjugate base of H 3 P O 4 from the given options. A conjugate base is what remains after an acid donates a proton ( H + ).
Finding the Conjugate Base To find the conjugate base of H 3 P O 4 , we need to remove one proton ( H + ) from it. This means we subtract one H from the formula and decrease the charge by 1.
Determining the Formula Starting with H 3 P O 4 , removing one H + gives us H 2 P O 4 . Since we removed a positive charge, the overall charge becomes -1. Therefore, the conjugate base is H 2 P O 4 − .
Selecting the Correct Option Comparing our result with the given options, we find that H 2 P O 4 − is one of the choices.
Examples
Understanding conjugate bases and acids is crucial in many chemical reactions, especially in biological systems. For example, the phosphate buffer system in our blood, involving H 2 P O 4 − and H P O 4 2 − , helps maintain a stable pH, which is vital for enzyme activity and overall health. This buffering action prevents drastic changes in acidity or alkalinity, ensuring our body functions properly.
