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Calculate the standard enthalpy change (∆H°) for the precipitation reaction between aqueous solutions of silver nitrate (AgNO3) and sodium chloride (NaCl) to form solid silver chloride (AgCl), given that 50.0 mL of 0.100 M AgNO3 and 50.0 mL of 0.100 M NaCl were combined in a calorimeter and the temperature change was recorded as -2.5°C.

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To calculate the standard enthalpy change  H  for the precipitation reaction, we need to first determine the heat  q  released during the reaction, and then divide it by the moles of the limiting reactant.The balanced chemical equation for the precipitation reaction is:AgNO3 aq  + NaCl aq   AgCl s  + NaNO3 aq First, we need to determine the limiting reactant. Since both solutions have the same volume  50.0 mL  and concentration  0.100 M , they have the same number of moles:moles of AgNO3 = moles of NaCl = 50.0 mL  0.100 mol/L = 0.00500 molSince the stoichiometry of the reaction is 1:1, both reactants are consumed at the same rate, and there is no limiting reactant in this case.Next, we need to calculate the heat  q  released during the reaction. We can use the formula:q = mcTwhere m is the mass of the solution, c is the specific heat capacity of the solution, and T is the temperature change.Assuming the specific heat capacity of the solution is the same as water  c = 4.18 J/gC  and the density of the solution is approximately the same as water  1 g/mL , we can calculate the mass of the solution:mass of the solution = volume of the solution  density of the solution =  50.0 mL + 50.0 mL   1 g/mL = 100.0 gNow we can calculate the heat  q  released:q =  100.0 g    4.18 J/gC    -2.5C  = -1045 JSince the heat is negative, it means the reaction is exothermic.Finally, we can calculate the standard enthalpy change  H  by dividing the heat  q  by the moles of the limiting reactant  in this case, either AgNO3 or NaCl :H = q / moles of limiting reactant = -1045 J / 0.00500 mol = -209000 J/molTherefore, the standard enthalpy change for the precipitation reaction is -209 kJ/mol.

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