Which of the following is a weak acid?

A)HN03
B)H3P04
C)NH3
D)C03^2-
E)OH

Look in your text or notes at the Ka for weak acids. If a Ka is listed it is a weak acid. If not it is a strong acid (or an incomplete table.

H3PO4

To determine which of the following is a weak acid, we need to understand the concept of weak acids and identify their characteristics. A weak acid is an acid that only partially dissociates in water, resulting in a relatively low concentration of hydrogen ions (H+).

Let's analyze each option:

A) HNO3: Nitric acid (HNO3) is a strong acid, as it completely dissociates into H+ and NO3-. Therefore, this option is not a weak acid.

B) H3PO4: Phosphoric acid (H3PO4) is also not a weak acid. It is a moderately strong acid that partially dissociates in water but has multiple dissociation steps.

C) NH3: Ammonia (NH3) is not an acid at all but rather a weak base. It accepts the hydrogen ions (H+) and acts as a proton acceptor.

D) CO3^2-: Carbonate ion (CO3^2-) is a base, specifically a moderately strong base. It can accept the H+ ions and act as a proton acceptor.

E) OH: Hydroxide ion (OH-) is a strong base, as it quickly accepts H+ ions and acts as a proton acceptor. It is not a weak acid.

Based on the explanations above, none of the options listed are weak acids.