Question

Calculate the enthalpy change for the dissolution of 10 g of sodium hydroxide in 100 g of water at a temperature of 25°C, given that the final temperature of the solution is 26.5°C and the specific heat capacity of the solution is 4.18 J g⁻¹ K⁻¹. (Assume that the heat released is absorbed by the solution and there is no heat lost to the surroundings.)

Answer 1

To calculate the enthalpy change for the dissolution of sodium hydroxide, 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, and T is the change in temperature.First, let's find the mass of the solution. Since we have 10 g of sodium hydroxide and 100 g of water, the total mass of the solution is:m = 10 g  NaOH  + 100 g  H2O  = 110 gNext, we need to find the change in temperature. The initial temperature is 25C and the final temperature is 26.5C, so the change in temperature is:T = 26.5C - 25C = 1.5CNow we can plug the values into the formula:q =  110 g    4.18 J g K    1.5C q = 688.47 JSince the heat is released during the dissolution process, the enthalpy change is negative:H = -688.47 JSo, the enthalpy change for the dissolution of 10 g of sodium hydroxide in 100 g of water at 25C is -688.47 J.