Many solutes that must move into and out of cells exist in either a protonated or ionized form, or they have functional groups that can be either protonated or ionized. Simple molecules such as CO2CO2, H3PO4H3PO4 (phosphoric acid), and NH3NH3 (ammonia) are in this category, as are organic molecules with carboxylic acid groups, phosphate groups, and/or amino groups.

Instead of ammonia, consider the uptake of acetic acid. CH3COOH, an important intermediate in several biological pathways. What is the charged form in this case?

The correct answer is acetate (CH₃COO⁻)

Explanation:

Acetic acid (CH₃COOH) is a well-known organic acid. Since its dissociation constant is low (≅ 1.7 x 10⁻⁵), it belongs to the group of weak acids. Its pKa is aproximately 4.8, so at physiological pH (7.4), it losses the proton from the carboxylic group and forms the negatively charged molecule CH₃COO⁻ (acetate).

out of these options:

ability to burn paper

pure sodium reacting violently with water

the boiling point of water

helium does not tend to react with anything

i would say this is a physical property:

helium does not tend to react with anything

why? :

i said helium does not tend to react with anything because well, it reacts to ! but ability to burn paper, pure sodium reacting violently with water, & the boiling point of water are chemical or

physical properties: the properties of a substance that can be observed without changing the chemical makeup of the substance

chemical properties: properties of a substance relating to the chemical nature and reactivity of the substance