A student is given the task of determining the enthalpy of reaction for the reac
ID: 482871 • Letter: A
Question
A student is given the task of determining the enthalpy of reaction for the reaction between HCl (aq) NaOH(aq). The following materials are available. The student may select from the glassware listed in the table below. The student selects two 100 mL beakers, uses them to measure 50 mL each of 1.00 M HCl(aq) 1.00 M NaOH(aq) solution, and measures an initial temperature of 24.5 degree C for each solution. Then the student pours the two solutions into an insulated cup, stirs the mixture, covers the cup, and records a maximum temperature of 29.9 degree C. Is the experimental design sufficient to determine the enthalpy of reaction to a precision of two significant figures? Justify your answer. List two specific changes to the experiment that will allow the student to determine the enthalpy reaction to a precision of three significant figures. Explain. A second student is given two solutions. 75.0 mL of 1.00 M HCl and 75.0 mL of 1.00 M NaOH, each at 25.0 degree C. The student pours the solutions into an insulated cup, stirs the mixture, covers the cup, and records the maximum temperature of the mixture. The student calculates the amount of beat evolved in the experiment to be 4.1 kJ. Calculate the student's experimental value for the enthalpy of reaction, in kJ/mol_rxn. The student assumes that the thermometer and the calorimeter do not absorb energy during the reaction. Does this assumption result in a calculated value of the enthalpy of reaction that is higher than, lower than, or the same as it would have been bad the heat capacities of the thermometer and calorimeter been taken into account? Justify your answer. One assumption in interpreting the results of the experiment is that the reaction between HCl(aq) and NaOH(aq) goes to completion. Justify the validity of this assumption in terms of the equilibrium constant for the reaction. A third student calculates a value for the enthalpy of reaction that is significantly higher than the accepted value. Identify a specific error in procedure made by the student that will result in a calculated value for the enthalpy of reaction that is higher than the accepted value. (Vague statements like "human error" or "incorrect calculations" will not cam credit.) Explain how the error that you identified in part (c)(i) leads to a calculated value for the enthalpy of reaction that is higher than the accepted value.Explanation / Answer
ANS: a)
(i)The key techniques for obtaining accurate resultsof enthalpy of reaction are starting with a dry calorimeter, measuring solution volumes precisely, and determining T accurately.
(ii) To improve the accuracy of result,
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.