Suppose you are titrating an acid solution with a base solution of known concentration. To calculate the concentration of the acid solution, use three steps. 1. Use the { (a) delivered volume (b) volume reading} of base { (a) after (b) to reach (c) before} the endpoint and the known concentration of the base solution to find the { (a) moles (b) mass (c) concentration} of base used. 2. Use the { (a) molar mass (b) dilution equation (c) molar ratio} to find the moles of acid from the moles of base. 3. Divide the moles of acid by the volume of { (a) base solution before (b) acid solution before (c) acid solution after} the titration to find the concentration of acid.