APS Science Curriculum Unit Planner Grade Level/Subject Chemistry Stage 1: Desired Results Enduring Understanding Topic 6 Solutions: Solutions concentrations can be understood by looking at molar relationships. Acids and Bases are special types of solutions. Correlations Unifying Understanding Behavior of solutions can be explained by interactions at the particle level. VA SOL CH.4 The student will investigate and understand that chemical quantities are based on molar relationships. Key concepts include c) solution concentrations; and d) acid/base theory; strong electrolytes, weak electrolytes, and nonelectrolytes; dissociation and ionization; ph and poh; and the titration process CH.5 The student will investigate and understand that the phases of matter are explained by kinetic theory and forces of attraction between particles. Key concepts include g) colligative properties. NSES (grade level) AAAS Atlas Essential Questions How do features of the atom at the particle level explain the behavior of the atom? How does the unique nature of solute-solvent interaction explains the solution process? What are the different ways that solution concentrations are expressed? How can concentrations of solutions affect chemical interactions? What are the characteristics that define an acid and a base? What are the properties of acids and bases? How is acidity measured? What are the uses of titrations? How are colligative properties quantified using solution concentration? 1
Knowledge and Skills Students should know: Mixtures maybe homogeneous or heterogeneous. Solute is defined as the part of a solution being dissolved. The solvent is the part of the solution doing the dissolving. Solutions may be composed of any combination of phases of matter. Solid/Solid solutions are called alloys. Molarity = moles/dm3 or moles of solute/l of solution. [ ] refers to molar concentration. When solutions are diluted, the moles of solute present initially remain. The saturation of a solution is dependent on the amount of solute present in the solution. Solutions may be unsaturated or saturated. Under unique situations, some solutions may be supersaturated. The terms concentrated and dilute are qualitative terms Ionic substances may dissociate into ions in solutions. Solubility may be graphed as a function of temperature and pressure. Solutions may be defined as electrolytes or non electrolytes. The degree of solubility of a substance in a solvent is dependent on forces of attraction and the general rule is like dissolves like. Two important classes of compounds are acids and bases. Acids and bases are defined by several theories. According to The Arrhenius theory of, acids are characterized by their sour taste, low ph, and the fact that they turn litmus paper red. According to Tthe Arrhenius theory of, bases are characterized by their bitter taste, slippery feel, high ph, and the fact that they turn litmus paper blue. According to The Bronsted-Lowry theory of, acids are proton donors, whereas bases are proton acceptors. Acids and bases dissociate in varying degrees. Strong electrolytes dissociate completely. Weak electrolytes dissociate partially. Non-electrolytes do not dissociate ph is a number scale ranging from 0 to 14 that represents the acidity of a solution. The ph number denotes hydrogen (hydronium) ion concentration. The poh number denotes hydroxide ion concentration. The higher the hydronium [H3O+] concentration, the lower the ph. ph + poh = 14 Strong acid-strong base titration is the process that measures [H++] and [OH--]. Indicators show color changes at certain ph levels. A liquid s boiling point and freezing point are affected by changes in atmospheric pressure. A liquid s boiling point and freezing point are affected by the presence of certain solutes. Students should be able to: perform calculations involving the molarity of a solution, including dilutions. interpret solubility curves. differentiate between the defining characteristics of the Arrhenius theory of acids and bases and the Bronsted-Lowry theory of acids and bases. identify common examples of acids and bases, including vinegar and ammonia. compare and contrast the differences between strong, weak, and non-electrolytes relate the hydronium ion concentration to the ph scale. perform titrations in a laboratory setting using indicators. examine the polarity of various solutes and solvents in solution formation. 2
Stage 2: Assessment Evidence Prior Knowledge and Skills Basic Algebra Rules for Significant Figures Mole Calculations Stoichiometry Formative Assessment Summative Assessment Student participation Laboratory Reports Homework (readings, questions, and problems) Tests and Quizzes Laboratory assessment understanding models Stage 3: Learning Plan References to Adopted Materials Prentice Hall Chemistry Text Chapter 2 Matter and Change Section 2.2 Mixtures pp.44-47 Chapter 15 Water and Aqueous Solutions Chapter 16 Solutions Chapter 19 Acids, Bases and Salts Guided Reading and Study Workbook: Chapter 2 pp.13-14 Chapter 15 pp159-167 Chapter 16 pp.168-175 Chapter 19 pp.209-218 Formatted: Font: 11 pt Holt Chemistry Text Chapter 1 - The Science of Chemistry,Section 3- How is Matter Classified? Chapter 13 Solutions Chapter 15 Acids and Bases Study Guide Chapter 1 p.1-7 Chapter 13 p.104-114 Chapter 15 p.123-132 Suggested Investigations Kool-aid Solubility Lab Calculate the molarity of kool-aid solutions. Discuss spectroscopy by comparing colors of concentrated vs. dilute solutions Conductivity Lab Testing the Conductivity of Electrolyte and Non-Electrolyte Solutions Small Scale Titration Lab Titration of Vinegar Lab Colligative Properties Making Ice Cream Prentice Hall Activities Teacher Demo Electrolytes and Non Electrolytes TE p.453 p.453 Small Scale Lab: Electrolytes p.470 Inquiry Lab: Salt and the Freezing Point of Water 3
Teacher Demo Solubility of Gases TE p.475 Teacher Demo Reactive Acids TE p.588 LM p. 179 Lab 28 Water of Hydration LM p.189 Lab 30 Factors Affecting Solution Formaton LM p.247 Lab 40 Estimation of ph LM p. 251 Lab 41 Reactions of Acid LM p. 255 Lab 42 Neutralization Reactions Holt Activities Activity TE p. 482 Edible Example of Freezing Point Depression Teacher Demo TE p.483 Insta-Freeze Teacher Demo TE p546 Effects of ph on Chlorophyll Stability Outdoor Education Applications Water Quality Testing at the Outdoor Lab Resources Web Sites http://www.chem.purdue.edu/gchelp/ - Visualization and Problem Solving for General Chemistry Section on Solutions Explorelearning.com ph Analysis Gizmo- Test the acidity of common substances using ph paper. Materials including soap, lemon juice, milk, and oven cleaner can be tested by comparing the color of ph strips to a standard scale. Colligative Propertie Gizmo - Determine how the physical properties of a solvent are dependent on the number of solute particles present. Measure the vapor pressure, boiling point, freezing point, and osmotic pressure of pure water and a variety of solutions. Compare the effects of four solutes (sucrose, sodium chloride, calcium chloride, and potassium chloride) on these physical properties. http://phet.colorado.edu/ - Fun, interactive, research-based simulations of physical phenomena from the PhET project at the University of Colorado. Acid and Base Solutions-How do strong and weak acids differ? Use lab tools on your computer to find out! Dip the paper or the probe into solution to measure the ph, or put in the electrodes to measure the conductivity. Then see how concentration and strength affect ph. Can a weak acid solution have the same ph as a strong acid solution? ph scale - Test the ph of things like coffee, spit, and soap to determine whether each is acidic, basic, or neutral. Visualize the relative number of hydroxide ions and hydronium ions in solution. Switch between logarithmic and linear scales. Investigate whether changing the volume or diluting with water affects the ph. Or you can design your own liquid! Salt and Solubility - Add different salts to water, then watch them dissolve and achieve a dynamic equilibrium with solid precipitate. Compare the number of ions in solution for highly soluble NaCl to other slightly soluble salts. Relate the charges on ions to the number of ions in the formula of a salt. Calculate Ksp values. 4
Videos Prentice Hall Chemistry Alive! Field Trips Chemistry of Soft Water The Story of Suds Cool Clear Water Discovery LearningEducation (www.discoveryeducation.com) Elements of Chemistry: Acids, Bases and Salts- Acids and bases are two different classes of compounds that are fundamental to the functioning of our world. When they combine, acids and bases produce salts. Students explore the chemistry of acids and bases and focus on the ph scale, an ingenious measurement of the amount of acidity and basicity of compounds. The program concludes by illustrating how the level of acids and bases contribute to processes as varied as acid rain and the functioning of the cells in our bodies (9 segments, 20:00) Chemistry Connections: Explaining the Strengths of Acids and Bases- An experiment comparing acidic solutions in relationship to their ph and conductivity leads to a definition of strong and weak acids. A similar procedure is followed for bases. Students develop equilibrium expressions for acids and bases and the Ka and Kb are then used to define strong and weak acids and bases. [5 segments, 29:05] Chemistry Connections: Acid-Base Indicators - Common substances are used to reveal how and why indicators change color in the presence of acids or bases. Demonstrates universal indicators and universal indicator strips. Students are challenged to design an experiment that determines the relative ph of several solutions using only indicators. Industrial uses for indicators are examined as well. [5 segments, 29:05] Field Trips Outdoor Lab Health of the Stream at the outdoor lab. ph and Water testing kits Other None noted. 5