Which of the following is a Bronsted-Lowry base but not a Lewis base?

a) H2O
c) CN–
e) all choices are both a B/L and Lewis base.
b) CO3–2
d) NH3

need help deciding

Draw the Lewis electron dot structure. Bases have a lone pair of electron they can donate. Do these have that? All of them are B/L bases.

To determine which of the options is a Bronsted-Lowry base but not a Lewis base, we need to understand the definitions of these two types of bases.

A Bronsted-Lowry base is a substance that can accept a proton (H+ ion) from another substance. It is defined based on its ability to donate or accept protons in a chemical reaction.

A Lewis base, on the other hand, is a substance that can donate a pair of electrons to form a covalent bond. It is defined based on its ability to donate electrons in a chemical reaction.

Now let's examine the options:

a) H2O - Water (H2O) can both accept a proton (acting as a base) and donate a pair of electrons (acting as a Lewis base). So, it is both a Bronsted-Lowry base and a Lewis base.

c) CN- - Cyanide ion (CN-) can accept a proton (acting as a base) but it also has a lone pair of electrons that it can donate (acting as a Lewis base). So, it is both a Bronsted-Lowry base and a Lewis base.

e) All choices are both a Bronsted-Lowry base and a Lewis base. - This statement implies that all options can accept a proton (acting as a Bronsted-Lowry base) and donate a pair of electrons (acting as a Lewis base). Therefore, all choices belong to both categories.

b) CO3^-2 - Carbonate ion (CO3^-2) can accept a proton (acting as a base) but it does not have a lone pair of electrons to donate (not acting as a Lewis base). Therefore, it is a Bronsted-Lowry base but not a Lewis base.

d) NH3 - Ammonia (NH3) can both accept a proton (acting as a base) and donate a pair of electrons (acting as a Lewis base). So, it is both a Bronsted-Lowry base and a Lewis base.

Therefore, the correct answer is:

b) CO3^-2 - It is a Bronsted-Lowry base but not a Lewis base.