Chapter 4.pdf - Chapter 4 The Major Classes of Chemical...

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Chapter 4 The Major Classes of Chemical Reactions Dr. Shamindri M. Arachchige [email protected] Surge 117
2 The concentrationof a solution is given by the quantity of _____________ present in a given quantity of _______________. Molarity(M) is often used to express concentration.Volume (L) of solution moles solute Molarity = L soln mol solute M= Solution StoichiometryMany reactions take place in solution (aqueous). We conveniently measure solution volume, not mass of solution. Characteristic of a solution: Solute: A solution is a homogeneous mixture. _____________is dissolved in a ___________Solute: Solvent: The substance __________________________________________The substance ___________________________________________Aqueous Solutions:Solvent:Need a way to express the ratio of components in the mixture: Chapter 4 The Major Classes of Chemical Reactions
3 Two ways to prepare a solution of a given molarity: 1. From the pure substance: 2. By dilution of an existing solution: Example Problem: How do you prepare 500. mL of a1. From the pure substance: Example Problem: How do you prepare 325 mL of a 0.25 M solution of KNO3? Chapter 4 The Major Classes of Chemical Reactions
4 Chapter 4 The Major Classes of Chemical Reactions
Chapter 4 The Major Classes of Chemical Reactions5 Water as a Solvent Water is a polar molecule since it has uneven electron distribution and a bent molecular shape. Water readily dissolves a variety of substances. Water interacts strongly with its solutes and often plays an active role in aqueous reactions.
Chapter 4 The Major Classes of Chemical Reactions6 Electron distribution in molecules of H2and H2O. Water interacts strongly with its solutes and often plays an active role in aqueous reactions. First, we need to understand what happens when a soluble compound dissolves in water. The type of compound determines the process.
Ionic Compounds (metal + nonmetal) Solid eg. K2SO4attraction between oppositely charged particles holds ions together ++++++++++++-- ----Aqueous Solution Ionized: K2SO4(s) 2K+(aq) + SO42(aq) ++++++++++-----Note: polyatomic ions do not dissociate; these act as a unitChapter 4 The Major Classes of Chemical Reactions7 There should _________cations for every __________anion in K2SO4
Chapter 4 The Major Classes of Chemical Reactions
8 What happens when a soluble ionic compound is dissolved in water?
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