The two infinitive functions are adjective and noun.

Infinitive phrases can also be adverbs.

http://www.chompchomp.com/terms/infinitivephrase.htm

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Sorry, Amanda, but I know nothing about chemistry.

Actually, infinitives are not functions but verb forms. They are formed by the base form of a verb with the word "to" in front of it (e.g., to run, to eat, to sleep). In English grammar, infinitives can be used as different parts of speech, including as adjectives and nouns.

An infinitive used as an adjective is called an infinitive phrase. This typically consists of the infinitive and any accompanying words that modify or describe it. For example, in the sentence "I have a book to read," the infinitive phrase "to read" functions as an adjective modifying the noun "book."

An infinitive used as a noun is called a gerund. A gerund is an -ing form of a verb that functions as a noun in a sentence. For example, in the sentence "I enjoy running," the gerund "running" acts as the direct object of the verb "enjoy."

To identify whether an infinitive is functioning as an adjective or a noun, you can examine its role within the sentence and the words it modifies or complements. Adjective infinitive phrases modify nouns or pronouns, while noun gerunds function as subjects, objects, or complements in a sentence.