2 Event DescriptionPurpose is for students to make and record observations.Students will test and characterize one pure substance.Based only on data they collect, answer a series of questions.
3 Competition Format A team of up to 2 students 50 minutes time 25 – 35 minutes for testing25 – 30 minutes for questions
4 Safety Requirements Students must bring and wear: Aprons or lab coats that cover the kneePants or skirts that cover the legs to the anklesClosed-toed shoesOSHA approved splash goggles with indirect ventsNo tasting or touching of powders is allowed
6 Students Should Bring pHydrion paper Hand lens 9V conductivity tester (no testers that run on 120V)Beral pipettes or eye droppersContainers for testing conductivity and solubilityOne or two 50 or 100 mL beakersClear plastic spot plateTest tube holder and rack if using test tubesSpatulaStirring rod
8 Event Leaders will Provide Definitely:The powder1.0 M NaOH1.0 M HClDistilled waterTwo different colored writing implementsMAY be provided:ThermometerBalanceHot plateObservation sheetAnything else the supervisor decides to distribute
9 Announcements Whether refills of the solid will be provided Whether there are any additional reagents and how to use themWaste disposal rulesClean up procedure
11 Testing the Solid First tests should be those that use entire sample If balances are available, weigh entire sampleBe familiar with different types of balancesSolubilityStart with a very small amountTest the solubility in every solvent available
12 Physical Properties Look at the solid with a lens Is it a powder or a crystal?Can you tell the shape of the crystalWhat is the color?What is the texture?
13 pH TestingTest the pH of the distilled water before testing the pH of the solutionsWhen you dissolve the powder in water, what is the pH?Bring the solution to the pH paperKnow the difference between a base and an acid
14 Conductivity Does the solution conduct electricity? If so, it contains ions and is an electrolyteKnow the difference between a strong and weak electrolyteKnow what a non-electrolyte is
15 Thermodynamics Measure the temperature of the water first When dissolving the substance in water, the temperature may go up or downIf no thermometer, hold test tube and see if change is apparentTake temperature readings at intervalsExothermic – temperature will riseEndothermic – temperature goes down
16 Gases Some solids give off gases when HCl is added Most common are the carbonates which give off carbon dioxideOthers are sulfites, sulfides, and nitratesNotice the color of the gas and odorUse proper technique for odorKnow how to measure the pH of a gasTo test for HCl gas, put wet pH paper in the test tube, as the gas is evolved. The color of the pH paper should change accordingly.
17 PrecipitationSome ions in water cause other ions to precipitate or form a solidWhat are the characteristics of the solid?Be aware that some precipitates will go back into solution as more reagent is added
18 SaturationHow much solid you have to add to make the solution saturated.Take 10 ml of distilled water and slowly add your solid while stirringYou will see solid floating when you cannot dissolve anymore.Some solids dissolve more slowly than others.
19 CompetitionStudents should number there data sequentially as it is collectedPoints are given based on the quality of the observationWrong answers have no pointsAnswers given to questions that cannot be backed by an observation are given minimum point value
20 Practice Practice using household powders Divide up the work Salt, Sugar, Baking soda, Epsom salts, BoraxDivide up the workHave the same student do the same work for each powderMake a table of your dataCheck to see if you are consistentStart learning vocabularyUse the Merck Index to check the properties of the powders you are testing