< Mentor Note -- thread moved to HH from the technical PF forums, so no HH Template is shown > Hello! So our teacher puts some really hard questions in acids and bases exams, and I would like someone to help me find similar questions and know how to solve these questions.. So the first lessons were about acids and bases, and the lesson talked in general about acids and bases ( properties, arrhenius/bronsted lowry/lewis , acid ionization and base dissociation, naming acids , etc) But then in the exam he gave us some challenging questions : write the ionization reaction for the following compound : al(h2o)6 3+ ( weak acid) While solving the sample problems all the questions were pretty straightforward acids like HCl + H2O --> H3O+ + CL- but now i found this weird acid .... [ al(h2o)6 3+ ( weak acid) ] I searched online to find the answer and found it : Al (H2O)6 3+ <---double arrows---> Al(OH)(H2O)5 2+ and H+ problem is, we usually solve with H3O+ not with H+... ( I know they're the same thing but I'm totally unfamiliar with the H+ thing...) can someone help with this question? how did we find the answer? and what are similar questions that can come like this ( hard acid/base ionization/dissociation problems like this).... Second challenging question : Geologist drops HCl on a rock , gas bubbles form. What might he conclude about the gas and rock ? gas: carbon dioxide rock : contains carbonate mineral? I didn't know these correct answers on the exam, but what are some similar problems to this one that can occur in the exam? and how can I study for the "harder" problems since the book's examples are too straightforward?