Sodium Thiosulfate Reaction

eLearning 2009 Publication No. 91860 prize of reaction of Sodium Thiosulfate and Hydrochloric Acid ordinate Laws Introduction The purpose of this demonstration is to investigate the effect of sodium thiosulfate submergence on the swan of reply of sodium thiosulfate with hydrochloric acid. The reception, which flummoxs solid southward, will be followed by measu sonorousness the while needed for the reply mixture to function opaque. The results will be analyzed graphically to determine the order of reaction the mathematical relationship between the reactant constriction and the rate.Concepts Kinetics Order of reaction post law Concentration Materials Hydrochloric acid solution, HCl, 2 M, 25 mL Sodium thiosulfate solution, Na2S2O3, 0. 15 M, 150 mL Distilled or deionized water Beakers, 100-mL, 5 Graduated cylinders, 50- or 100-mL, 2 Graduated cylinders, 10-mL, 5 Overhead projector or light box Permanent marker Stirring rods Stopwatch or whiler Safety Precautions Hydr ochloric acid solution is corrosive to eyes and strip. It is more or less toxic by ingestion and inhalation. Sodium thiosulfate solution is a luggage compartment tissue irritant.The reaction of sodium thiosulfate and hydrochloric acid generates sulfur dioxide gas, which is a skin and eye irritant. Perform this demonstration in a well-ventilated lab only. subdue contact of all chemicals with eyes and skin. Wear chemical splash goggles, temperature-resistant gloves, and chemical-resistant apron. amuse review current Material Safety Data Sheets for additional safety, handling, and presidency information. Procedure 1. Label quintuplet 100-mL beakers 15 and clean the stinker of each beaker. 2. Draw a large X across the bottom on the placeside of each beaker.Place the beakers on an overhead projector stage or a light box so that students can view the X. 3. apply separate graduated cylinders for the solution and water, measure and add the required measuring rods of 0. 15 M s odium thiosulfate and distilled water to each beaker. Be as distinct as possible. Beaker 0. 15 M Na2S2O3 Distilled Water 1 50. 0 mL 0 mL 2 40. 0 mL 10. 0 mL 3 30. 0 mL 20. 0 mL 4 20. 0 mL 30. 0 mL 5 10. 0 mL 40. 0 mL 4. Have students calculate the final concentration of sodium thiosulfate in each beaker 15. 91860 011509 Flinn scientificTeaching Chemistry eLearning Video series 5.Record the following information in a data table Beaker, multitude of Na2S2O3 solution, volume of distilled water, concentration of Na2S2O3, reaction cartridge holder (sec), and 1/reaction season (reaction rate). See the Sample Data and Results table in the Discussion section. 6. taproom 5. 0 mL of 2 M hydrochloric acid into each of five 10-mL graduated cylinders. 7. Starting with beaker 1, carefully add the HCl all in unitary pour to the sodium thiosulfate solution. Stir the solution once with a breathing in rod and immediately start timing. 8. Stop timing when the black X is no longer visible. Reco rd the reaction time in seconds in the data table. . Repeat steps 7 and 8 with beakers 25. 10. envision 1/reaction time for each trial. Plot concentration vs. time and concentration vs. 1/time on separate graphs. Disposal cheer consult your current Flinn Scientific compose/Reference Manual for worldwide guidelines and specific procedures governing the disposal of laboratory waste. Collect the leftover reaction mixtures and filter to separate the solid sulfur product. The sulfur may be disposed of in a landfill according to Flinn Suggested Disposal Method 26a. The sink in may be neutralized and disposed of down the drain with unnecessary water according toFlinn Suggested Disposal Method 26b. Tips This natural process may be performed as a chemical demonstration with classroom participation or as a student activity. The contents of the beakers project well on an overhead projector and the time to the disappearance of the black X is easily seen and measured. The reaction may be downsized for a student lab activity. Carry out individual trials in separate wells in a 6-well reaction plate or in small medicine cups. If students will be doing the experiment in the lab, it is a good idea for them to start with beaker 5, because it takes the yearlong time. The activity may also be performed as a co-op class exercise with different groups investigating different variables, including the effect of HCl concentration and the effect of temperature. The reaction rate is zero-order with observe to HCl. Empty the beakers and clean them good using paper towels to learn the sulfur. If the colloidal sulfur is allowed to sit in the beakers for an extended time, it will be much more difficult to remove the deposits from the glass. To achieve better mixing of the reactants, add the hydrochloric acid using a 10-mL luer-lock plastic syringe (without needle).Squirt the acid using a fair amount of force. When pass up concentrations of sodium thiosulfate are used, the rat e law does not appear to be as simple as predicted in this experiment. At lower concentrations, the reaction appears to be closer to 3/2-order in sodium thiosulfate and 1/2-order in hydrochloric acid. The reaction time is more difficult to measure at lower concentrations because the onset of turbidity is more gradual. Both the overall chemical equation and the mechanism for the decomposition of sodium thiosulfate are more interlocking than suggested by Equation 1.The reaction is acid-catalyzed, which means that the acid concentration mustiness have some bearing on the rate in call of producing an equilibrium concentration of HS2O3 ions, The HS2O3 ion is a reactive intermediate, reacting further with additional S2O32 ions to produce polymeric ions containing multiple S atoms. When the chain of S atoms in a polymeric ion becomes long enough, it closes in on itself to form a ring of elemental sulfur (S8). S2O32 + H+ < > HS2O3 HSSO3 + nS2O32 HS(S)nSO3 + nSO32 HSSnSO3 & lt > H+ + SSnSO3 SS7SO3 S8 + SO32 2 2009 Flinn Scientific, Inc. in all Rights Reserved. 91860 Discussion Sodium thiosulfate reacts with hydrochloric acid to form sulfur and sulfur dioxide (Equation 1). Na2S2O3(aq) + 2HCl(aq) S(s) + SO2(g) + 2NaCl(aq) Equation 1 The kinetics of the reaction can be analyzed by graphing the concentration of Na2S2O3 as a function of two reaction time and 1/time. A plot of concentration versus time gives a curved line, which levels off as it approaches the x-axisthe reaction slows down as the reactant concentration decreases. The rate of a reaction is inversely proportional to reaction time.A plot of concentration of versus 1/time gives a straight line. The rate is directly proportional to concentration, and the reaction appears to be first order with respect to sodium thiosulfate concentration. Sample Data and Results Beaker 1 2 3 4 5 Volume of Na2S2O3 (mL) 50 40 30 20 10 Volume of H2O (mL) 0 10 20 30 40 Na2S2O3, M 0. 15 0. 12 0. 090 0. 060 0. 030 Reaction time (sec) 22. 5 27. 3 35. 1 60. 0 159. 1 Reaction rate (1/time, sec1) . 0444 . 0367 . 0285 . 0167 . 00629 clxxx 160 140 120 100 80 60 40 20 0 0. 00 Effect of concentration on reaction time 0. 05 0. 10 0. 15 0. 20 Na 2 S2 O3 Concentration, M 0. 07 0. 6 0. 05 0. 04 0. 03 0. 02 0. 01 0 0. 00 Effect of concentration on reaction rate 0. 05 Na 2 S2 O3 Concentration, M 0. 10 0. 15 0. 20 3 2009 Flinn Scientific, Inc. All Rights Reserved. 91860 Connecting to the National Standards This laboratory activity relates to the following National Science study Standards (1996) Unifying Concepts and Processes Grades K12 Evidence, models, and explanation Constancy, change, and measurement Content Standards Grades 912 Content Standard A Science as interrogation Content Standard B Physical Science, structure and properties of matter, chemical reactions, motions and forcesFlinn ScientificTeaching Chemistry eLearning Video Series A video of the Rate of Reaction of Sodium Thiosulfate and Hydrochloric Acid activity, presented by Annis Hapkiewicz, is available in Rate Laws, part of the Flinn ScientificTeaching Chemistry eLearning Video Series. Materials for Rate of Reaction of Sodium Thiosulfate and Hydrochloric Acid are available from Flinn Scientific, Inc. Materials required to perform this activity are available in the Reaction Order and Rate Laws student science laboratory Kit available from Flinn Scientific.Materials may also be purchased separately. catalogue No. Description AP4864 H0034 S0114 AP1572 GP1010 GP2005 GP2015 Reaction Order and Rate LawsStudent Laboratory Kit Hydrochloric Acid, 3 M, 500 mL Sodium Thiosulfate Pentahydrate, Reagent, 500 g Timer, Stopwatch, Flinn Beaker, Borosilicate Glass, 100 mL Graduated Cylinder, Borosilicate Glass, 10-mL Graduated Cylinder, Borosilicate Glass, 50-mL Consult your Flinn Scientific Catalog/Reference Manual for current prices. 4 2009 Flinn Scientific, Inc. All Rights Reserved. 91860