Calculations on gen. chem section are straight forward. Most formulas will need to be memorized. In other words, they will not have the formulas outside the problem for him to conveniently use. However, the answer choices will typically show the set up used to calculate the correct answer. So if he knows how to set it up, then he will not have any problems. It's all in how you set it up that leads you to the correct answer.
The DAT isn't worried about deriving answers (for the most part) until you arrive at the quantitative reasoning section. That's why it's not necessary to have a calculator for this exam. The DAT is testing his overall knowledge of the material like:
"Does he know how to set up a gas law problem?"
"Can he work basic stoichiometry and nuclear phenomena(half life)?"
"Does his have a basic idea of hybridization and orbital diagrams?"
Some constants will be given if necessary. He won't be short-changed if that's what you want to know.