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Here's a precise problem for the student to solve: Calculate the standard enthalpy change for the neutralization of 50 mL of 0.10 M hydrochloric acid (HCl) with 50 mL of 0.10 M sodium hydroxide (NaOH) at 25°C, given that the specific heat capacity of the solution is 4.18 J/(g °C) and the density of the solution is 1.00 g/mL.

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ago by (430 points)
To calculate the standard enthalpy change for the neutralization of HCl with NaOH, we can use the following equation:q = mcTwhere q is the heat released or absorbed, m is the mass of the solution, c is the specific heat capacity, and T is the change in temperature.First, we need to determine the moles of HCl and NaOH in the solution:moles of HCl = volume  concentration = 0.050 L  0.10 mol/L = 0.005 molmoles of NaOH = volume  concentration = 0.050 L  0.10 mol/L = 0.005 molSince the moles of HCl and NaOH are equal, the reaction will go to completion, and the neutralization reaction is as follows:HCl aq  + NaOH aq   NaCl aq  + HO l Now, we need to find the mass of the solution:mass = volume  density =  0.050 L + 0.050 L   1000 mL/L  1.00 g/mL = 100 gNext, we need to find the change in temperature  T . Since the reaction is exothermic, the temperature of the solution will increase. The standard enthalpy change for the neutralization of a strong acid and a strong base is approximately -57.1 kJ/mol. We can use this value to find the change in temperature:q = -57.1 kJ/mol  0.005 mol = -0.2855 kJ = -285.5 JNow, we can use the equation q = mcT to find the change in temperature:-285.5 J =  100 g  4.18 J/ g C  TSolving for T:T = -285.5 J /  100 g  4.18 J/ g C   = -0.682 CSince the reaction is exothermic, the temperature of the solution will increase by 0.682 C. The standard enthalpy change for the neutralization of 50 mL of 0.10 M HCl with 50 mL of 0.10 M NaOH at 25C is -285.5 J or -0.2855 kJ.

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