Science, Tech, Math › Science How to Prepare a Solution Chemistry Quick Review of Solution Preparation Share Flipboard Email Print COLIN CUTHBERT/SCIENCE PHOTO LIBRARY / Getty Images Science Chemistry Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated May 10, 2019 Here's a quick overview of how to prepare a solution when the final concentration is expressed as M or molarity. You prepare a solution by dissolving a known mass of solute (often a solid) into a specific amount of a solvent. One of the most common ways to express the concentration of the solution is M or molarity, which is moles of solute per liter of solution. Example of How to Prepare a Solution Prepare 1 liter of 1.00 M NaCl solution. First, calculate the molar mass of NaCl which is the mass of a mole of Na plus the mass of a mole of Cl or 22.99 + 35.45 = 58.44 g/mol Weigh out 58.44 g NaCl.Place the NaCl in a 1-liter volumetric flask.Add a small volume of distilled, deionized water to dissolve the salt.Fill the flask to the 1 L line. If a different molarity is required, then multiply that number times the molar mass of NaCl. For example, if you wanted a 0.5 M solution, you would use 0.5 x 58.44 g/mol of NaCl in 1 L of solution or 29.22 g of NaCl. Important Points to Remember Molarity is expressed in terms of liter of solution, not liters of solvent. To prepare a solution, the flask is filled to the mark. In other words, it is incorrect to a 1 liter of water to a mass of sample to prepare a molar solution.Sometimes it's necessary to adjust the pH of a solution. To do this, add enough water to dissolve the solute. Then add an acid or base solution dropwise (usually a hydrochloric acid or HCl solution for acid or sodium hydroxide or NaOH solution for a base) to reach the desired pH. Then add more water to reach the mark on the glassware. Adding more water won't change the pH value.