DESCRIPTION: Students will work cooperatively to answer a series of questions or complete a task involving the science processes of chemistry focused in the areas of kinetics and aqueous solutions. No reference materials allowed. If needed, calculators will be supplied. Do not bring a calculator!
Safety Requirements: Students must bring and wear aprons or lab coats and OSHA approved chemical splash goggles with indirect vents. THE COMPETITION: TEAM OF UP TO: 2 APPROXIMATE TIME: 50 minutes
The competition will consist of a seris of stations that include activities similar to those in first year high school courses. These stations could include hands-on activities, interpretation of experimental data (graphs, diagrams, photographs, etc.), and/or observation of an experiment set up and running. Contestants may or may not be rotated through stations. Supervisors are encouraged to use computer or calculator sensors/probes wherever possilbe or provide students with data sets collected by such sensors/probes following demonstration of the data collection. Data will be presented in a tabular and/or graphic format and students will be expected to interpret the data. Students should be aware that nomenclature, formula writing, and stoichiometry are essential tools of chemistry and may be included in the event at any time. Stoichiometry includes, for example, such abilities as mole conversions and percentage yield. For purposes of nomenclature and formula writing, students are expected to know the symbols and charges for the following ions by memory: nitrate, carbonate, phosphate, acetate, sulfate, ammonium, bicarbonate, and hydroxide. Students should know and be able to use the "ite" form of an ion, which is one less oxygen then the "ate" form, where this is applicable. Further, students should be able to use the periodic table to obtain the charge for monoatomic ions. For example, Na+, S2-, etc.
1. The event will cover theory and application of areas in kinetics and aqueous solutions. The following will be provided if needed: a)periodic table b)calculator c)any constants needed and d) any polyatmoic ions not included in the group to be memorized.
2. THe lab portion may be run in microscale.
3. Cleanup should occur after all materials have been returned or a penalty may be given.
4.ALl measurements must be rocorded with correct significant figures and units. All calculations must also include correct significant figures and units. Station smight include the following topics:
KINTEICS
Effects of the following on rates of reactions: temeprature, concentration, particle size, and catalysts. At the regional level, teams will NOT be asked to determine rate laws experimentally or from data provided. At the state and national levels, teams will be asked to determine rate constants with correct units. AQUEOUS SOLUTIONS
Students must be able to calculate solution concentrations given quantities of solute and solvent, and to calculate quantities of material required to produce a solution of specified concentration. Molarity, molality, mass percentage, and ppm may be required. At the state and national levels, conversions between concentration units may be required. Tasks will be chosen from the following:
1. Prepare a solution of specified concentration, including appropriate weighing technique and use of glassware.
2. Use the concept of density to experimentally determine the concentration of a solution.
3. Determing solution concentration using a series of standard absorbencies and Beer's Law.
4. Use freezing point depression to determine the molar mass of a solute.
5. Use titration to determine an unknown concentration. SCORING: Points will be awarded for correct answers and/or proper technique. Time may be limited at each station, but time will not be used as a tiebreaker or for scoring. All ties will be broken by selected questions chosen at the discretion of the event supervisor. These questions may or may not be identified to the students.
