Concept explainers
A solution is made by dissolving 15.0 g sodium hydroxide in approximately 450 mL water. The solution becomes quite warm, but after it is allowed to return to room temperature, water is added to bring the volume to 500.0 mL of solution.
(a) Calculate the pH and pOH in the final solution.
(b) Why would we wait for it to return to room temperature?
(c) If the mass of the water used to initially dissolve the sodium hydroxide were exactly 450 g and the temperature of the water increased by 8.865 °C, how much heat was given off by the dissolution of 15.0 g of solute? Assume the specific heat of the solution is 4.184 J/g. K. What is the molar heat change for the dissolution of sodium hydroxide (known as the enthalpy of solution, ΔHsol)?
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Chemistry: Principles and Practice
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