Investigating the chemistry of the OH group
To test for a carboxylic acid, mix with a carbonate and look for effervescence. CO2(g) emitted, can test with limewater.
To test for phenol group, mix with neutral FeCl3 solution and look for pale yellow colour turning purple.
Useful books for revision
Revise A2 Chemistry for Salters (OCR A Level Chemistry B)
Salters (OCR) Revise A2 Chemistry