Question: is 37 hcl by weight or volume?
Answer: Considering 37% as the maximum solubility of HCl, you can calculate the molarity using the solution density (1.2 g/mL) and HCl's molar mass (36.46 g/mol). For 1000 mL of solution, you will have 1200g of weight, of which 37% is HCl: 444g.