Two solutions,50.0 mL of 1.00 M BaCl₂(aq)and 50.0 mL of 1.00 M Na₂SO₄(aq),both initially at 21.5 °C,are added to a calorimeter with a total heat capacity,after the solutions are added,of 1.10 kJ/ °C and the temperature rises to 22.7 °C.Determine q_rxn per mole of BaSO₄(s)formed in the reaction. A)-26.4 kJ/mol B)+26.4 kJ/mol C)-2.64 kJ/mol D)+2.64 kJ/mol

Question

Quizplus · Accepted Answer

First, we need to write the balanced chemical equation for the reaction between BaCl2 and Na2SO4:

BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2NaCl(aq)

Next, we need to calculate the amount of heat released or absorbed by the reaction using the equation:

qrxn = -CΔT

where qrxn is the heat absorbed or released by the reaction, C is the total heat capacity of the calorimeter, and ΔT is the temperature change.

In this case, qrxn = -(1.10 kJ/°C)(22.7 °C - 21.5 °C) = -1.32 kJ

Since we have equal amounts of BaCl2 and Na2SO4, the limiting reagent is either one. Let's assume that BaCl2 is the limiting reagent and that all of it is converted to BaSO4.

From the balanced chemical equation, we see that 1 mole of BaCl2 produces 1 mole of BaSO4, so the reaction produces 0.0500 moles of BaSO4.

Therefore, the heat released per mole of BaSO4 formed is:

qrxn/mol BaSO4 = (-1.32 kJ) / (0.0500 mol) = -26.4 kJ/mol

The negative sign indicates that the reaction is exothermic (i.e. heat is released). Therefore, the answer is A, -26.4 kJ/mol.

Two Solutions,50