Propylene glycol (C) is produced by the liquid-phase hydrolysis of propylene oxide (A). Sulfuric acid catalyzes the reaction. With excess water (B), the reaction is zero order with respect to water, and first order in propylene oxide, having a rate of reaction designated by (-ra). A continuous stirred-tank reactor (CSTR) system, having a volume V and a residence time t, is to be designed for this reaction. The fractional conversion of A in the CSTR is XA. The molar flow rate of A is FAo in the feed and FA in the product. The concentration of A is CA, in the feed and CA in the product. The design equation for the CSTR can be written as: