03_ReactionRates_PostLab_Spring 24

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Arizona State University *

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116

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Chemistry

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Apr 3, 2024

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Reaction Rates Name Date of Work TOTAL: 30 points

Insert Last Name Reaction Rates Page 2 of 12 CHM 116 POST-LAB Reaction Rates: Determining Order of Reactants and Rate Law 1. Insert ONE picture of yourself in full PPE here ( include the 24 -Well plate) in your PPE picture ). **Remember to (1) show your full body so that we see you are wearing shoes; (2) wear your safety glasses, long sleeves shirt and gloves; (3) cover your lower legs, including ankles (socks are required, even in Arizona); (4) tie back long hair in a ponytail or a bun; (5) remove jewelry. Insert Picture Here

Insert Last Name Reaction Rates Page 3 of 12 2. Insert a picture HERE of all the materials you will be using for this experiment (do NOT use the picture provided in the Procedure). Include a numbered figure legend below the picture. Materials

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Insert Last Name Reaction Rates Page 4 of 12 Determining Rate Law This reaction rate data is analyzed and used to determine the rate law for the reaction between HCl and Na 2 S 2 O 3 . 2HCl(aq) + Na 2 S 2 O 3 (aq) → S(s) + SO 2 (aq) + H 2 O(l) + 2NaCl(aq) The general form for the rate law for the above reaction between HCl and Na 2 S 2 O 3 is written as: Rate = k[ HCl ] x [ Na 2 S 2 O 3 ] y When the concentration of one chemical is changed, the other chemical’s concentration is held constant. When testing for the order of [HCl], [Na 2 S 2 O 3 ] is held constant. When testing for [Na 2 S 2 O 3 ], [HCl] is held constant. This means that any change in reaction rate between experiments can be attributed to the change in just one of the reactants (the other is held constant). In doing so, the variables m and n can be separately computed via a ratio. Part 1: Determining Order for HCL 3. Data Table 1: Varying the concentration of HCl while keeping the concentration of Na 2 S 2 O 3 constant. Table 1: Varying the concentration of HCl Number of drops Concentrations (M) Reaction Time(sec) Reaction Rate Well # HCl Water Na 2 S 2 O 3 HCl initial Na 2 S 2 O 3 initial HCl final Na 2 S 2 O 3 final Trial 1 Trial 2 Average Sec -1 C1, D1 12 0 8 1M 0.3 M 0.6 M 0.12 M 23.9 23.4 23.65 0.42 C2, D2 6 6 8 0.5 M 0.3 M 0.3 M 0.21 M 31.4 28.6 30.0 .033 C3, D3 4 8 8 0.33 M 0.3M 34.6 M 32.6 M 34.6 32.6 33.6 .029

Insert Last Name Reaction Rates Page 5 of 12 4. Show your work for the following calculations: Determine the concentration (in molarity) of HCl and the concentration (in molarity) of Na 2 S 2 O 3 for each experiment in Part 1. These are just dilution calculations. 5. Show your work for the following calculations: Determine the initial reaction rate for each experiment in Part 1. Calculated [HCl] for : Wells C1 and D1: Wells C2 and D2: Wells C3 and D3: Calculated [ Na 2 S 2 O 3 ] for all wells (C1, D1, C2, D2, C3, D3) : Average Reaction Times : Wells C1 and D1: Wells C2 and D2: Wells C3 and D3: Initial Reaction Rates: Wells C1 and D1: Wells C2 and D2: Wells C3 and D3:

Insert Last Name Reaction Rates Page 6 of 12 6. Using the data from Table 1 , find the reaction order of HCl. This value is the “ x ” in the rate law for the reaction: Rate = k[ HCl ] x [ Na 2 S 2 O 3 ] y Use the initial rate of two experiments in which the concentration of HCl varied (from Table 1), but the concentration of Na 2 S 2 O 3 stayed the same. (use the Introduction document for reference). Show your work. Part 2: Determining Order for Na 2 S 2 O 3 7. Data Table 2: Varying the concentration of Na 2 S 2 O 3 while keeping the concentration of HCl constant. Table 2: Varying the Concentration of Na 2 S 2 O 3 Number of drops Concentrations (M) Reaction Time(sec) Initial Reaction Rate Well # HCl Water Na 2 S 2 O 3 HCl initial Na 2 S 2 O 3 initial HCl final Na 2 S 2 O 3 final Trial 1 Trial 2 Average Sec -1 C4, D4 8 0 12 1 M 0.3 M 0.6 M 0.18 M 18.1 18.5 18.3 .054 C5, D5 8 6 6 1 M 0.15 M 0.07 M 0.09 M 34.0 40.0 37.0 .027 C6, D6 8 8 4 1 M 0.1 M 0.8 M 0.06 M 59.0 65.1 62.05 .016

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Insert Last Name Reaction Rates Page 7 of 12 8. Show your work for the following calculations: Determine the concentration (in molarity) of HCl and the concentration (in molarity) of Na 2 S 2 O 3 for each experiment in Part 2. These are just dilution calculations. 9. Using the whole number values calculated in Questions 6 and 10, write down the rate law expression with the respective reaction orders for HCl and Na 2 S 2 O 3 . Calculated [ Na 2 S 2 O 3 ] for : Wells C4 and D4: Wells C5 and D5: Wells C6 and D6: Calculated [ HCl ] for all wells (C4, D4, C5, D5, C6, D6) :

Insert Last Name Reaction Rates Page 8 of 12 Rate= k[Na2S2O3]1[HCL]0 116 Online Lab Notebook Entry ( 5 Points) Purpose/Goal of Experiment: Planned Observations: Experiment Title: __________________________________________________ Date of Experiment: __________________________________________________ Student Name: __________________________________________________