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Next Generation Chemistry II
Kaye Truitt, Don Bratton, Tina WagnerMSMS
Qualitative Analysis of Six Common Substances Using
Patterns of Reactivity boric acid
cornstarch
magnesium sulfate
sodium bicarbonate
sodium chloride
sucrose
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)
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.
Qualitative Analysis
Compounds and reagents easily acquired Reagents:
Water, iodine, vinegar, NaOH, alcohol, heat
Minimal equipment needed
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
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.
Iodine Clock Kinetics
http://www.youtube.com/watch?v=C5tOEBmBAHg
Iodine Clock Kinetics
Chemical KineticsStudy of factors affecting the rate of reaction and of mechanism of reaction
Mechanism: Step-by-step molecular pathway of a reaction
Experimental chemistry
Iodine Clock Kinetics
Key Concept: Rate LawMathematical 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
Iodine Clock Kinetics
Key Concept: Rate ConstantRepresented by k in the rate law
Must be mathematically determined
Units vary with number of reactants and coefficients
Iodine Clock Kinetics
Key Concept: Reaction OrderExponents (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
Iodine Clock Kinetics
Rate Laws and MechanismsSome 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
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
Iodine Clock Kinetics
NGSS AlignmentHS-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.
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
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
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
Inquiry “twist”Determine a metals’ placement on the activity series based on whether hydrogen gas is evolved / produced.
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
