pH and POH of Strong Acids and Bases - AP Chemistry

NH3 should be the clear correct choice, since it is the only one having a pair of electrons that are available. The rest of the answer choices are all Lewis acids.

The conjugate base of an acid will be the same compound, short one H atom. ClO4– is the only one that meets this criterion.

A Lewis base is an electron-pair donor. Only PH3 has a pair of nonbonding electrons and can act as a donor.

The conjugate base has one less H atoms and one unit greater negative charge because of this. Thus, the correct answer is HC2O4–

A Lewis base is an electron-pair donor. N atoms have a valence of 5, and in the NH2NH2 compound, it is only bonded to another N atom and 2 H, so it's only using 3 of its 5 valence electrons to form these bonds. Thus, each nitrogen has a pair of unbonded electrons and can act as a Lewis base.

NH3 should be the clear correct choice, since it is the only one having a pair of electrons that are available. The rest of the answer choices are all Lewis acids.

The conjugate base of an acid will be the same compound, short one H atom. ClO4– is the only one that meets this criterion.

A Lewis base is an electron-pair donor. Only PH3 has a pair of nonbonding electrons and can act as a donor.

The conjugate base has one less H atoms and one unit greater negative charge because of this. Thus, the correct answer is HC2O4–

The Ka is the acid dissociation constant, and thus it is what determines how strong the acid is. Stronger acids dissociate to a greater extent and produce lower pH values.

The definition of a Bronsted-Lowry base is a species that has the ability to gain, or accept a proton (H+). Dissociating in solution is part of the Arrhenius definition of acids and bases, and Lewis acid are electron pair acceptors.

A Lewis base is an electron-pair donor. N atoms have a valence of 5, and in the NH2NH2 compound, it is only bonded to another N atom and 2 H, so it's only using 3 of its 5 valence electrons to form these bonds. Thus, each nitrogen has a pair of unbonded electrons and can act as a Lewis base.

NH3 should be the clear correct choice, since it is the only one having a pair of electrons that are available. The rest of the answer choices are all Lewis acids.

The conjugate base of an acid will be the same compound, short one H atom. ClO4– is the only one that meets this criterion.

A Lewis base is an electron-pair donor. Only PH3 has a pair of nonbonding electrons and can act as a donor.

The conjugate base has one less H atoms and one unit greater negative charge because of this. Thus, the correct answer is HC2O4–

A Lewis acid is a species that can accept an electron pair. In the BCl3 molecule, B does not have a complete octet (3 covalent bonds, thus 6 electrons around it rather than 8). Thus, it can accept another electron pair, making it a Lewis acid.

Conjugate acid has one more H+ than the compound with which it is being compared. Thus, H2CO3 is the conjugate acid of HCO3–.

This question is simply testing your memorization of strong and weak acids. Of the list, you should recognize that nitric acid is the only strong acid, and the rest of the choices are weak.