What prediction can be made of the relative strengths of the conjugate bases of: H₂S,HCl,SiH₄,PH₃? A)PH₂^- SiH₃^- HS^- Cl^- B)SiH₃^- PH₂^- HS^- Cl^- C)Cl^- HS^- PH₂^- SiH₃^- D)HS^- Cl^- SiH₃^- PH₂^- E)Cl^- PH₂^- SiH₃^- HS^-

Question

What prediction can be made of the relative strengths of the conjugate bases of: H₂S,HCl,SiH₄,PH₃? A)PH₂^- > SiH₃^- > HS^- > Cl^- B)SiH₃^- > PH₂^- > HS^- > Cl^- C)Cl^- > HS^- > PH₂^- > SiH₃^- D)HS^- > Cl^- > SiH₃^- > PH₂^- E)Cl^- > PH₂^- > SiH₃^- > HS^-

Quizplus · Accepted Answer

The strength of a conjugate base can be determined by the stability of the resulting ion after donating a proton. In this case, the order of stability can be predicted by looking at the electronegativity of the central atom and the size of the resulting ion. SiH₃^- has the most stable resulting ion because the negative charge is located on a larger and less electronegative atom (Si) compared to the other molecules. PH₂^- has the second most stable resulting ion since P is larger and less electronegative than S, but not as large or as a low in electronegativity as Si. H₂S is the third most stable because the resulting ion is located on a small and highly electronegative atom (S). HCl is the least stable conjugate base because Cl is the smallest and most electronegative of the four central atoms.

What Prediction Can Be Made of the Relative Strengths of the Conjugate