This work provides a correlation study of the role of the following cognitive variables on problem solving in elementary physical chemistry: scientific reasoning (level of intellectual development/developmental level), working-memory capacity, functional mental ("M") capacity, and disembedding ability (i.e., degree of perceptual field dependence--independence). Nine individual studies, with seven problems and with various samples of first-year undergraduate chemistry students at the University of Ioannina, were used. The problems were open-book, while the students were as a rule not supplied with the necessary data (facts, figures, values of constants, etc.). The results were analysed by calculating Spearman's [rho] and Pearson "r" correlation coefficients. In addition, the seven individual studies were combined using a quasi meta-analysis (n = 250). The main findings are: (1) scientific reasoning showed lack of correlation; (2) working-memory capacity also showed weak correlation, but stronger than scientific reasoning; and (3) functional "M"-capacity and disembedding ability played a very important role. The field may thus be of paramount importance in the novel (for the students) non-algorithmic problems used in this study. Implications of the findings are discussed.