what is the mol.weight (daltons) when the percent of mass is 1.5?
CREATE TABLE "composition_by_molecule_type" (
  "molecule" text,
  "percent_of_mass" text,
  "mol_weight_daltons" text,
  "molecules" text,
  "percent_of_molecules" text
);
SELECT "mol_weight_daltons" FROM "composition_by_molecule_type" WHERE "percent_of_mass"='1.5';