CHEMISTRY LAB

MICHIGAN SCIENCE OLYMPIAD COACHES WORKSHOP AT MSU

SATURDAY, DECEMBER 5, 2015

PRESENTED BY:

MIKE REED, REEDM@GHAPS.ORG

MICHIGAN SCIENCE OLYMPIAD BOARD MEMBER

AP CHEMISTRY TEACHER, GRAND HAVEN HIGH SCHOOL

HEAD COACH, GRAND HAVEN HIGH SCHOOL SCIENCE OLYMPIAD

From Michigan Science Olympiad: If you have not already registered and

paid for your team, go to http://miscioly.org/shop/

The deadline for registering and paying for your team is January 11th.

State bids are based on the number of primary teams registered and paid by the deadline.

See Sue West for more information regarding registration.

For coaches, students, and event supervisors:1.Read the rules.2.Know the rules.3.Follow the rules.

SAFETY FIRST!

GOGGLES

GOGGLES from sonic.org/eye_protectionCATEGORY C

Description: Indirect vent chemical/splash protection goggles. These seal tightly to the face completely around the eyes and have indirect vents constructed so that liquids do not have a direct path into the eye (or no vents at all). If you are able to see through the vent holes from one side to the other, they are NOT indirect vents

Corresponding ANSI designation/required marking: Z87 (followed by D3 is the most modern designation but, it is not a requirement)

Example: Indirect vent chemical/splash protection goggles

Notes: 

1. A goggle that bears the Z87+ mark and is an indirect vent chemical/splash protection goggle will qualify for all three Categories A, B & C

2. VisorGogs do not seal completely to the face, but are acceptable as indirect vent chemical/splash protection goggles

LAB COATS OR LAB APRONS

1. DESCRIPTION:

Teams will complete one or more tasks and answer a series of questions involving the science processes of chemistry focused in the areas of kinetics and gases.

A TEAM OF UP TO: 2 EYE PROTECTION: C APPROX. TIME: 50 min.

2. EVENT PARAMETERS:

a. Students: Each student must bring safety equipment and a writing implement and each team may bring two non-camera capability calculators and five 8.5” x 11” sheets of paper that may contain information on both sides in any form from any source (sheet protectors are permitted).

b. Supervisors: must provide reagents/glassware/references that are needed for the tasks (e.g., Periodic Table, table of standard reduction potentials, any constants needed).

c. Safety Requirements: Students must wear goggles, an apron or a lab coat and have skin covered from the neck down to the wrist and toes (gloves are optional, but if a host requires a specific type they must notify teams). Long hair, shoulder length or longer, must be tied back. Students who unsafely remove their safety clothing/goggles or are observed handling any of the material or equipment in an unsafe manner will be penalized or disqualified from the event.

3. THE COMPETITION:

a. The competition will consist of a series of tasks similar to those in first year high school courses. These tasks could include hands-on activities, questions about each topic, interpretation of experimental data (graphs, diagrams, etc.), and/or observation of an experiment set up & running.

b. Supervisors are encouraged to use computers or calculators with sensors/probes. Teams may be asked to collect data using probe ware that has been set up & demonstrated by the Supervisor or they may 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 & students will be expected to interpret the data.

c. Students should be aware that nomenclature, formula writing & Stoichiometry are essential tools of chemistry & may always be included in the event. Stoichiometry includes mole conversions & percentage yield. For purposes of nomenclature & formula writing, students are expected to know the symbols & charges for the following ions: nitrate, carbonate, phosphate, acetate, sulfate, ammonium, bicarbonate & hydroxide. Students should know how to use the “ite” form of anion (one less oxygen than the “ate” form). Students should be able to use the periodic table to obtain the charge for monatomic ions (e.g., Na+, S2-).

4. SAMPLE QUESTIONS:

a. Kinetics: Students will demonstrate an understanding of the principles of kinetics. They must be able to measure reaction rates and identify how and why reaction conditions (temperature, concentration, particle size, and catalysts) affect reaction rates. 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 laws from actual experimentation or data provided, and teams should also be able to determine rate constants with correct units.

b. Gases: Students will complete experimental tasks and answer questions related to the physical properties of gases, effect of greenhouse gases and ozone depletion on our climate, behavior of gases described by the following: Avogadro’s law, Boyle’s Law, Charles’ Law, Dalton’s law, Gay-Lussac’s law, Graham’s Law, and the ideal gas law. Students may be expected to complete labs/activities such as: Determine the: density of a gas, partial pressure of a gas, molar mass of a gas, relative rates of diffusion. Examine the relationship between: Pressure and volume, Pressure and temperature, Temperature and volume

5. SCORING:

Approximately Kinetics 50% and Gases 50%. Time may be limited at each task, but will not be used as a tiebreaker or for scoring. Ties will be broken by pre-selected questions.

Recommended Resources: All reference and training resources including the Chem/Phy Sci CD (CPCD) are available on the Official Science Olympiad Store or Website at www.soinc.org

See General Rules, Eye Protection & other Policies on www.soinc.org as they apply to every event.

SOINC.ORG Go to https://

www.soinc.org/frequently_asked_questions and https://www.soinc.org/official_rules_clarif to see frequently asked questions and rules clarifications for every event.

The Official Rules Clarifications and FAQs apply to all states and all tournaments and originate at the National level (please check your Regional or State Website for special updates pertaining to your regional or state events).

Which students should do Chemistry Lab?

Use the most experienced chemistry students possible AP Chemistry or IB Chemistry Honors Chemistry General Chemistry

Students should have good working knowledge of math as it applies to chemistry.

KEYS FOR COACHING

PRACTICE, PRACTICE, PRACTICE

DO AS MANY LABS DEALING WITH GASES AND KINETICS AS POSSIBLE

From the state event supervisor:

“Last year, the exam consisted of 8 questions worth a total of 64 points, and the experiment portion consisted of 36 points, bringing the total to 100 points. The experiment and exam are not created yet, however I would imagine that the same weight will be placed on the exam and experimental portion as last year.”

From the state event supervisor:“The kinetics questions will focus on determining rate laws and rate constants, and also understanding how different reaction conditions may change the reaction rate. The gases section will mainly focus on manipulating the ideal gas law to determine the relationship between different variables such as temperature and pressure. Relative diffusion rates of gases along with the partial pressure and molar mass of gases will also be examined.”

KINETICS: THE STUDY OF REACTION RATES Collision theory (particles must

collide effectively in order for a reaction to occur)Effective collisions occur between molecules with proper orientation, and sufficient energy (activation energy).

Reaction rate is determined by the frequency of effective collisions.

KINETICS Reaction rate is affected by:

Physical state of the reactants

Reactant concentrationReaction temperatureCatalysts or inhibitors

KINETICS Reaction rates are determined

experimentally by measuring the change in the concentration of reactants (decreasing) or the change in the concentration of products (increasing), over time. Reaction rates are always expressed as a positive quantity.

The average reaction rate for the reaction A → B is expressed as:

-Δ[A]/Δt, or, Δ[B]/Δt

KINETICSFor the reaction aA + bB → cC + dD, the general rate law for the reaction has the form Rate = k [A]m [B]n where k is the rate constant.

The rate law and the rate constant can only be determined experimentally.

The exponents m and n are called the reaction order with respect to each reactant, and are determined by comparing reaction rates with different initial concentrations of each reactant.

Reaction Order and Concentration Relationships:

Zero-order reactionsThe rate of the reaction is independent of the

concentration of a reactant.

First-order reactionsThe rate of the reaction depends on the

concentration of a reactant raised to the first power. (Double the concentration, double the rate)

Second-order reactionsThe rate of the reaction depends on the

concentration of a reactant raised to the second power, or, on the concentrations of two reactants each raised to the first power. (Double the concentration, quadruple the rate)

Rate = k [A]2 [B]0 = k [A]2

Second order w.r.t. AZero order w.r.t. B

Second order overall

Rate = k [NH4+] [NO2

-]First order w.r.t. NH4

+ First order w.r.t. NO2

- Second order overall

Rate = k [NO]2 [H2]Second order w.r.t. NO

First order w.r.t. H2

Third order overall

Zero-order vs. First-order

First-order

Second-order

Integrated Rate Laws in Linear Form

Zero-order

[A]t = -kt + [A]0

First-order

ln [A]t = -kt + ln [A]0

Second-order

1/[A]t = kt + 1/[A]0

Half-life Half-life is the time needed for the

concentration of a reactant to decrease to one-half of its original concentration, [A]t1/2 = ½ [A]0

First-order reactions: t1/2 = - ln ½ /k = 0.693/k Half-life is independent of original

concentrations Fast reactions have short half-lives Slow reactions have long half-lives All radioactive decay is first-order

Half-life of a First-order Reaction

Half-life The half-life for second-order (and

other) reactions depends on the original reactant concentration. Therefore, as the reaction proceeds, the time for the half-life changes.

t1/2 = 1/(k [A]0)

Low initial concentrations of reactants leads to longer half-lives

High initial concentrations of reactants leads to shorter half-lives

KINETICS EXPERIMENTS TO TRY Burning candle on electronic scale. Measure mass of

candle and time as candle burns. Determine change in mass over change in time (reaction rate).

React magnesium with hydrochloric acid. Measure the amount of time needed for a piece of magnesium to completely react with various concentrations of HCl. Use same volume of HCl and same mass of Mg every time. Calculate average reaction rates, determine order of reaction and rate constant.

React calcium carbonate (marble chips) with acid in container on electronic scale. Measure mass of reactants and time as CO2 is produced.

GASES Boyle’s Law

GASES Boyle’s Law: At constant temperature and

number of moles of gas, the volume and pressure of a gas in a closed container are inversely proportional to each other. PV = k

GASES Charles’s Law: At constant temperature and

number of moles of a gas, the volume and absolute temperature of a gas in a closed container are directly proportional to each other. V/T = k

GASES Other directly proportional gas laws:

Avogadro’s Law: V/n = k, at constant pressure and temperature

Amonton’s Law: P/T = k, at constant volume and number of moles

Ideal Gas Law: PV/nT = R, the ideal gas constant, = 0.08206 atm-L/mol-K

At standard temperature and pressure, STP, (273.15 K and 1atm), the molar volume of a gas is 22.41 L

GASES Other gas laws:

Dalton’s Law of Partial Pressures: The total pressure of a mixture of gases equals the sum of the individual partial pressures of each gas in the mixture. Ptotal = P1 + P2 + P3 + …

Gay-Lussac’s Law (the law of combining volumes): At a given pressure and temperature, the volumes of gases reacting with each other are in the ratios of small whole numbers.

GASES Other gas laws:

Graham’s Law of Effusion: The effusion rate of a gas is inversely proportional to the square root of its molar mass. (rate)(1/√) = k

GASES Determining the density of a gas:

D = m/V = nM/V = PM/RT Determining the molar mass of a gas:

M = DRT/P = mRT/PV Determining the partial pressure of a

gas:

P1 = X1Ptotal where X1 is the mole fraction

of a gas. X1 = n1/ntotal

DIFFUSION OF GASES Molecular Mass and Molecular Speed

DIFFUSION OF GASES Diffusion path of a gas molecule

GASES – OZONE DEPLETION

GASES – OZONE DEPLETION

GASES – EFFECT OF GREENHOUSE GASES

GASES – EFFECT OF GREENHOUSE GASES

QUESTIONS? See your friendly, neighborhood chemistry teacher.

Get a good AP Chemistry textbook.

Look up labs to do and information on the internet. http://www.scioly.org/wiki/index.php/Test_Exchange#Chemistry_Lab

GO FORTH AND MAKE CHEMISTS!