Next Generation Chemistry II

1. Next Generation Chemistry II Kaye Truitt, Don Bratton, Tina Wagner MSMS

2. Qualitative Analysis of Six Common Substances Using Patterns of Reactivity • boric acid • cornstarch • magnesium sulfate • sodium bicarbonate • sodium chloride • sucrose

3. Standards • MS Chemistry Framework: • Inquiry 1 • F: data analysis (DOK 3) • G: draw conclusions from data to use technology for formal presentation (DOK 3) • Physical Science 2 • A: describe and classify matter based on physical and chemical properties (DOK 1) • E: compare properties of compounds according to their type of bonding (DOK 1) • Physical Science 3 • C: classify chemical reactions by type (products and solubility rules)

4. Standards • Next Generation Science Standards: • HS-PS1-2: Construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of patterns of chemical properties. • Science & Engineering Practices: • Planning and carrying out investigations • Disciplinary Core Ideas: • PS1.A The PT orders elements horizontally by the number of protons in the atom's nucleus and places those with similar chemical properties in columns. The repeating patterns of the table reflect patterns of outer electron states. • Cross-cutting Concepts: Patterns • Different patterns may be observed at each of the scales at which a system is studied and can provide evidence for causality in explanations of phenomena.

5. Qualitative Analysis • Compounds and reagents easily acquired • Reagents: • Water, iodine, vinegar, NaOH, alcohol, heat • Minimal equipment needed

6. Qualitative Analysis • Substances have similar physical properties regarding appearance • Use patterns in reactivity and other physical properties such as melting point to identify substances • STEM: qualitative analysis is critical in chemical industry, food industry, medicinal chemistry

7. Qualitative Analysis • Uses critical thinking to isolate one compound at a time. • For inquiry-based activity, eliminate flow chart and give reactivity patterns for types of compounds (i.e., carbonate reactions with acids) and allow students to create a flow chart for analysis.

8. Iodine Clock Kinetics • http://www.youtube.com/watch?v=C5tOEBmBAHg

9. Iodine Clock Kinetics • Chemical Kinetics • Study of factors affecting the rate of reaction and of mechanism of reaction • Mechanism: Step-by-step molecular pathway of a reaction • Experimental chemistry

10. Iodine Clock Kinetics • Key Concept: Rate Law • Mathematical expression of rate with respect to concentration of reactants only NH4+ + NO2- N2 + 2 H2O Rate = k[NH4+][NO2-] aA + bB cC + dD Rate = k[A]m[B]n

11. Iodine Clock Kinetics • Key Concept: Rate Constant • Represented by k in the rate law • Must be mathematically determined • Units vary with number of reactants and coefficients

12. Iodine Clock Kinetics • Key Concept: Reaction Order • Exponents (m and n) in rate law • Often expressed as “The order of the reaction with respect to X”. • Can be 0, and sometimes even fractional

13. Iodine Clock Kinetics • Rate Laws and Mechanisms • Some reactions have multiple steps NO2 (g) + CO (g)  NO (g) + CO2 (g) NO2 (g) + NO2 (g)  NO3 (g) + NO (g) (slow) NO3 (g) + CO (g)  NO2 (g) + CO2 (g) (fast) • The steps of a reaction mechanism must sum to the overall reaction equation • The slowest step determines the rate and the rate law

14. Iodine Clock Kinetics • 2010 MCF Alignment (Chemistry) • 4.d Describe and identify factors affecting the solution process, rates of reaction, and equilibrium. (DOK 2) • And most of the inquiry standards

15. Iodine Clock Kinetics • NGSS Alignment • HS-PS1-5: Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.

16. Iodine Clock Kinetics • Materials (different from video) • 0.05 M KI solution • 1% starch solution • 0.01 M sodium thiosulfate solution • 1.0 M sulfuric acid solution • 0.05 M hydrogen peroxide solution • Glassware

17. Iodine Clock Kinetics • It is important to have a baseline to measure how factors affect kinetics • Ensure that all students measure the baseline reaction several times to get an average • Slight differences in execution can affect the timing • The base reaction on the handout takes approximately 1 minute to react

18. 5 microscale reactions to produce various gases (CO2, NO2, NH3, O2, H2) • Splint tests to identify CO2, O2, H2 • Lime water also identifies CO2 • Litmus test to identify NH3 • Brown gas = NO2

19. Inquiry “twist” • Determine a metals’ placement on the activity series based on whether hydrogen gas is evolved / produced.

20. Mississippi 2010 Framework INQUIRY - 1. Apply inquiry-based and problem-solving processes and skills to scientific investigations. Physical Science 3. Develop an understanding of the periodic table. • c. Classify chemical reactions by type. (DOK 2) Single displacement, double displacement, synthesis (combination), decomposition, combustion, or precipitation. Products (given reactants) or reactants (given products) for each reaction type

21. dbratton@themsms.org • http://bratton.themsms.org • ktruitt@themsms.org • cwagner@themsms.org