chit-chat vs chew the fat

chit-chat is a noun but chew the fat is not a noun.

Word	Noun	Adjective	Verb	Adverb
chit-chat	Yes	No	Yes	No
chew the fat	No	No	Yes	No

As verbs, chit-chat and chew the fat are synonyms defined as:

chit-chat and chew the fat: talk socially without exchanging too much information

Other synonyms of chit-chat include chaffer, chat, chatter, chitchat, claver, confab, confabulate, gossip, jaw, natter, shoot the breeze, visit.

chit-chat (noun)	chew the fat (noun)
light informal conversation for social occasions

chit-chat (verb)	chew the fat (verb)
talk socially without exchanging too much information	talk socially without exchanging too much information