for each of the following pairs, determine which acid is the stronger acid.
A. H2S, HS-
B. H2SO3, H2SeO3
C. HBr, H2Se
D. HIO4, HIO3
E. H2S, H2O
a. H2S
b. H2SO3
c. HBr
d. HIO3
e. H2S
correct
To determine which acid is stronger in each pair, we need to compare the acidity of the acids based on their acid dissociation constant (Ka) or their tendency to donate a hydrogen ion (H+).
A. H2S, HS-:
H2S is a weak acid, while HS- is its conjugate base. The conjugate base of a weak acid is always a stronger base than the original acid. Therefore, HS- is a stronger base than H2S, meaning H2S is the stronger acid.
B. H2SO3, H2SeO3:
To determine which acid is stronger, we need to compare the atomic size and electronegativity of the non-metal central atoms. In this case, Sulfur (S) is larger and less electronegative than Selenium (Se). Larger atoms have weaker bonds, making it easier for them to release hydrogen ions, and less electronegative atoms are less likely to attract the electrons in the hydrogen-oxygen bond. Therefore, since H2SO3 has a larger central atom with lower electronegativity, it is a stronger acid than H2SeO3.
C. HBr, H2Se:
Similar to the previous case, we compare the atomic size and electronegativity of the non-metal central atoms. Bromine (Br) is larger and less electronegative than Selenium (Se). Hence, HBr is a stronger acid than H2Se.
D. HIO4, HIO3:
Again, we compare the atomic size and electronegativity of the non-metal central atoms. In this case, both atoms are iodine, so we need to look at the number of oxygen atoms attached to the central atom. An increase in the number of oxygen atoms increases the stability of the molecule, making it less likely to dissociate and release hydrogen ions. Therefore, HIO4 is a stronger acid than HIO3.
E. H2S, H2O:
To determine which of these two compounds is the stronger acid, we need to compare their Ka values. H2O is a very weak acid and has a Ka value close to 1x10^-15. On the other hand, H2S is a much stronger acid with a Ka value of about 1x10^-7. Therefore, H2S is a stronger acid than H2O.
In summary:
A. H2S is the stronger acid.
B. H2SO3 is the stronger acid.
C. HBr is the stronger acid.
D. HIO4 is the stronger acid.
E. H2S is the stronger acid.