To find the conjugate base of [tex]\( H_3PO_4 \)[/tex] (phosphoric acid), we'll follow these steps:
1. Understanding the Concept:
- The conjugate base of an acid is formed by removing one proton ([tex]\( H^+ \)[/tex]) from the acid.
2. Identify the Acid:
- The given acid is [tex]\( H_3PO_4 \)[/tex].
3. Remove One Proton ([tex]\( H^+ \)[/tex]):
- The chemical formula for [tex]\( H_3PO_4 \)[/tex] indicates it has three protons. Removing one proton means reducing the number of hydrogen atoms by one.
- [tex]\( H_3PO_4 - H^+ = H_2PO_4^- \)[/tex]
4. Determine the Resulting Ion:
- After removing one proton from [tex]\( H_3PO_4 \)[/tex], we get [tex]\( H_2PO_4^- \)[/tex]. This is the conjugate base of [tex]\( H_3PO_4 \)[/tex].
5. Review the Choices:
- A. [tex]\( HPO_4^{2-} \)[/tex]
- B. [tex]\( H_4PO_4^+ \)[/tex]
- C. [tex]\( PO_4^{3-} \)[/tex]
- D. [tex]\( H_2PO_4^- \)[/tex]
6. Select the Correct Choice:
- From the choices given, the correct answer is [tex]\( H_2PO_4^- \)[/tex].
Thus, the conjugate base of [tex]\( H_3PO_4 \)[/tex] is [tex]\( H_2PO_4^- \)[/tex]. Therefore, Choice D is the correct answer.
