Two solutions,initially at 24.60°C,are mixed in a coffee cup calorimeter.When a 100.0 mL volume of 0.100 M AgNO₃ solution is mixed with a 100.0 mL sample of 0.200 M NaCl solution,the temperature in the calorimeter rises to 25.30°C.Determine the DH°_rxn for the reaction as written below.Assume that the density and heat capacity of the solutions is the same as that of water.
NaCl(aq) + AgNO₃(aq) → AgCl(s) + NaNO₃(aq) DH°_rxn = ?

Question

Quizplus · Accepted Answer

First, we need to calculate the amount of heat absorbed by the solution using the following formula: q = m * c * ΔT where q is the amount of heat, m is the mass of the solution (which we can assume to be 100 g since the density is the same as water), c is the specific heat capacity of the solution (which we can also assume to be the same as water, 4.184 J/g°C), and ΔT is the change in temperature (which is 0.7°C). q = 100 g * 4.184 J/g°C * 0.7°C q = 292.88 J Next, we need to calculate the moles of each reactant using the following formula: moles = concentration * volume For NaCl: moles NaCl = 0.200 M * 0.100 L moles NaCl = 0.020 mol For AgNO₃: moles AgNO₃ = 0.100 M * 0.100 L moles AgNO₃ = 0.010 mol According to the balanced chemical equation, the reaction produces 1 mole of AgCl. Therefore, the amount of heat absorbed per mole of AgCl formed is: ΔHrxn = q / moles AgCl ΔHrxn = 292.88 J / 0.010 mol ΔHrxn = -29,288 J/mol Converting this to kilojoules per mole: ΔHrxn = -29.288 kJ/mol Therefore, the best choice is B, -59 kJ.

Two Solutions,initially at 24