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Lab Report: Reaction Order and Rate Laws

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Objective: To study the effect of reactant concentration on the rate of the reaction between sodium thiosulfate and hydrochloric acid and to determine the order of each reactant and the rate law for the reaction.

2 HCI(aq) + NaS2O3 (aq) --> S(s) + SO2 (aq) + H2O(l) + 2NaCL(aq)


(a) Calculate the initial and final concentrations as needed to complete tables 1 and 2.
(b) Calculate the average reaction time for each reaction by adding the times for the two trials and dividing by 2.
(c) Calculate the reaction rate by taking the inverse of the average reaction time.
(d) Write the rate law for the reaction.

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Observations/Data 1:

Assume that each drop is 1 ml.

Final HCl

Trial 1 => Vtotal = 12 ml + 8 ml = 20 ml
nHCl = 12 ml * 1 M = 12 * 10-3 moles = 12 mmol
=> Final HCl => 12 mmol / 20 ml = 0.6 M

Trial 2 => Vtotal = 6 ml + 6 ml + 8 ml= 20 ml
nHCl = 6 ml * 1 M = 6 * 10-3 moles = 6 mmol
=> Final HCl => 6 mmol / 20 ml = ...

Solution Summary

This solution provides a guide with completed trial data, calculations and answers for this type of lab report.

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