3. Answer the following questions about an experiment in which CaCO3(s) is combined with HCl(aq), re — Kinetics, Calorimetry, Thermodynamics Chemistry Question
Problem Context
3. Answer the following questions about an experiment in which CaCO3(s) is combined with HCl(aq), represented by the following balanced equation.
CaCO3(s) + 2 HCl(aq) → CaCl2(aq) + CO2(g) + H2O(l)
(a) Write the balanced net ionic equation for the reaction.
A student performs an investigation to study factors that affect the rate of the reaction. In each trial the student combines 50.0 mL of HCl(aq) at 21.2° C with 1.00 g of CaCO3(s) and measures the time required for the reaction to go to completion. The data are given in the following table.
(b) The student correctly identifies that trial 5 is inconsistent with the other trials. Explain why the student’s claim is correct using the data in the table.
(c) Based on the reaction conditions and the collisions that occur between particles, explain the reason for the difference in the reaction times for trial 2 and trial 3.
(d) The student claims that the reaction is zero order with respect to HCl(aq). Do you agree or disagree with the student’s claim? Justify your answer using the student’s data.
(e) The HCl(aq) was present in excess in all trials of the experiment. Determine the molarity of the HCl(aq) in the beaker after the reaction is complete in trial 2. Assume that the volume of the mixture remains constant at 50.0 mL throughout the trial. (The molar mass of CaCO3 is 100.09 g/mol.)
CaCO3(s) + 2 HCl(aq) → CaCl2(aq) + CO2(g) + H2O(l)
In order to measure the enthalpy of the reaction shown, the student repeats trial 1 by mixing 50.0 mL of HCl(aq) with 1.00 g of CaCO3(s) using a coffee cup calorimeter. The student records the temperature of the system every 20 seconds. The data are given in the following table.
(f) Is the reaction endothermic or exothermic? Justify your answer using the information in the table.
(g) Based on the experimental data, the mass of the system is 51.0 g, and the specific heat of the reaction mixture is 4.0 J / (g · ° C).
(i) Calculate the magnitude of heat transfer, q , in joules.
(ii) Calculate the enthalpy of reaction in units of kJ/mol rxn . Include the algebraic sign on your answer.