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

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

dbratton@themsms.orghttp://bratton.themsms.org

ktruitt@themsms.org

cwagner@themsms.org