Science, Tech, Math › Science Aqueous Solution Chemical Reaction Problem Print Wikimedia Commons/LHcheM 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. 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. Learn about our Editorial Process Updated on January 10, 2020 This worked chemistry example problem demonstrates how to determine the number of reactants needed to complete a reaction in an aqueous solution. Problem For the reaction: Zn(s) + 2H+(aq) → Zn2+(aq) + H2(g)Determine the number of moles H+ that is required to form 1.22 mol H2.Determine the mass in grams of Zn that is required to form 0.621 mol of H2 Solution Read More Reactions in Water or Aqueous Solution By Anne Marie Helmenstine, Ph.D. Part A: You may wish to review the types of reactions that occur in water and the rules that apply to balance aqueous solution equations. Once you have set them up, balanced equations for reactions in aqueous solutions work in exactly the same way as other balanced equations. The coefficients signify the relative number of moles of substances participating in the reaction. From the balanced equation, you can see that 2 mol H+ is used for every 1 mol H2. If we use this as a conversion factor, then for 1.22 mol H2: moles H+ = 1.22 mol H2 x 2 mol H+ / 1 mol H2moles H+ = 2.44 mol H+ Part B: Similarly, 1 mol Zn is required for 1 mol H2. To work this problem, you need to know how many grams are in 1 mol of Zn. Look up the atomic mass for the zinc from the Periodic Table. The atomic mass of zinc is 65.38, so there is 65.38 g in 1 mol Zn. Plugging in these values gives us: mass Zn = 0.621 mol H2 x 1 mol Zn / 1 mol H2 x 65.38 g Zn / 1 mol Znmass Zn = 40.6 g Zn Answer 2.44 mol of H+ is required to form 1.22 mol H2.40.6 g Zn is required to form 0.621 mol of H2 Cite this Article Format mla apa chicago Your Citation Helmenstine, Anne Marie, Ph.D. "Aqueous Solution Chemical Reaction Problem." ThoughtCo, Apr. 5, 2023, thoughtco.com/aqueous-solution-chemical-reaction-problem-609538. Helmenstine, Anne Marie, Ph.D. (2023, April 5). Aqueous Solution Chemical Reaction Problem. Retrieved from https://www.thoughtco.com/aqueous-solution-chemical-reaction-problem-609538 Helmenstine, Anne Marie, Ph.D. "Aqueous Solution Chemical Reaction Problem." ThoughtCo. https://www.thoughtco.com/aqueous-solution-chemical-reaction-problem-609538 (accessed March 30, 2024). copy citation