I have taught and tutored chemistry multiple times. The math skills that are often missing are basic algebraic manipulations, unit conversions, scientific notation, and most notably, order of operations and calculator usage. (i.e 3 over 4 x 5 is entered 3÷4x5 instead of 3÷(4x5) or 3÷4÷5). The ability to understand significant figures is also VERY challenging to most students. Basic logarithms/exponentials are required to calculate pH and H+ concentrations. You can learn that as you go, but having had previous exposure to logarithms is helpful. I have found that most students who have "passed" algebra, aren't actually proficient at it.