because ENTHALPY (Heat of Formation) is a state property, it doesn’t matter how

because ENTHALPY (Heat of Formation) is a state property, it doesn’t matter how we prepare a sample. IF we end of with a solution of sodium chloride (salt, NaCl) in water, we know its heat of formation. It doesn’t matter whether we started with solid NaCl and dissolved it in water or we started with solutions of NaOH and HCl in water and reacted them to make NaCl, water, and some excess heat. The heat of formation of aqueous NaCl is always -407.1 kJ/mol.
We’ll return to the Beyond Labz Calorimetry lab to measure the Heat of Reaction when we mix a solution of hydrochloric acid (HCl) with a solution of sodium hydroxide (NaOH). This reaction is EXOTHERMIC (it releases heat) and it’s important to note that it also forms water as a product, along with salt (NaCl). We’ll also measure the heat of solution of salt in water. The procedure is here
(MS Word doc on Canvas) or here on OneDriveLinks to an external site.; please fill in the data tables, answer the questions, and submit the completed report via Canvas. You can also download the PDF version here
Note: your numerical results may not exactly match the known enthalpy values for these two processes. That’s OK, just make sure to report your results clearly and answer the questions in the report form.
This reaction is an amusing classroom demonstration, because if you start with equal volumes of HCl and NaOH solutions at equal concentrations, the final volume is MORE than you expect — that’s the extra water formed in the reaction. The volume in the 1L volumetric flask is approximately 18 mL over the 1000 mL mark:
Thank you

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