select the stronger base. how do i know this?
1.SeO42− or SO42−
2.BrO− or BrO2−
To compare the strength of bases, you need to evaluate their relative abilities to accept or donate protons (H+ ions). Here are the steps to determine which base is stronger:
1. Look at the central atom: In both cases, the central atom is oxygen. Since oxygen is more electronegative than sulfur, the negative charge in SeO42− and SO42− is more stabilized in SeO42−. As a result, SeO42− is a stronger base than SO42−.
2. Consider the charge: SeO42− has a charge of −2, while SO42− also has a charge of −2. Since the charge is the same, you can skip this step for this comparison.
3. Examine the electron density: SeO42− has a larger size than SO42− due to the presence of a central selenium atom instead of sulfur. Larger atoms have more diffuse electron clouds, which means the negative charge in SeO42− is less concentrated compared to SO42−. Therefore, SeO42− has a higher electron density and is a stronger base than SO42−.
So, for the first comparison, SeO42− is the stronger base.
Now let's move on to the second comparison:
1. Look at the central atom: In both cases, the central atom is bromine. The oxidation state of bromine is different in BrO− (−1) and BrO2− (+3). The higher oxidation state in BrO2− makes it more electronegative and more stabilized, resulting in BrO2− being a stronger base than BrO−.
2. Consider the charge: BrO− has a charge of −1, while BrO2− has a charge of −1 as well. Since the charge is the same, you can skip this step for this comparison.
3. Examine the electron density: BrO2− has a higher electron density due to the presence of an additional oxygen atom bonded to bromine. The extra oxygen allows for more electron delocalization and increases the negative charge's stability in BrO2−. Consequently, BrO2− is a stronger base than BrO−.
Therefore, for the second comparison, BrO2− is the stronger base.
Remember, when comparing the strength of bases, factors such as electronegativity, size, and ability to stabilize the negative charge (electron density) must be considered.
I would look at the hydrolysis constant Kb.
SeO4^2- + HOH ==> HSeO4^- + OH^-
Kb for SeO4^2- = (Kw/k2 for H2SeO4)
For H2SO4 it is
Kb for SO4^2- = (Kw/k2 for H2SO4)
The best I could find for k2 H2SeO4 = 0.012 and for k2 for H2SO4 I found 0.013. Not much difference.