Question

Calculate the enthalpy change for the dissolution of 5 grams of sodium chloride in 50 mL of water if the temperature of the solution decreases from 25 °C to 21 °C. The density of the solution is 1.0 g/mL and the specific heat capacity of the solution is 4.18 J/g°C. (Assume the heat exchange between the solution and the surroundings is negligible)

Answer 1

To calculate the enthalpy change for the dissolution of sodium chloride, we can use the formula:q = mcTwhere q is the heat absorbed or released, m is the mass of the solution, c is the specific heat capacity of the solution, and T is the change in temperature.First, we need to find the mass of the solution. Since the density of the solution is 1.0 g/mL, we can calculate the mass as follows:mass of solution = volume of solution  density of solutionmass of solution = 50 mL  1.0 g/mL = 50 gNow, we can calculate the change in temperature:T = T_final - T_initialT = 21 C - 25 C = -4 CSince the temperature of the solution decreases, the dissolution of sodium chloride is an exothermic process, and the heat is released to the surroundings.Now, we can calculate the heat absorbed or released  q  using the formula:q = mcTq =  50 g  4.18 J/gC  -4 C q = -836 JThe enthalpy change for the dissolution of 5 grams of sodium chloride in 50 mL of water is -836 J.