A. Research Question What is the ΔH of NaOH when reacted with HCl? B. Theoretical Approach Hess’s Law states that the enthalpy change for a reaction that is carried out in a series of steps is equal to the sum of the enthalpy changes for the individual steps. This means that when you perform a reaction in multiple steps, the heat loss or gain is the same as if you did the reaction in just on step. In this experiment the reaction was split into two separate reactions. The change in temperature was recorded for each. Afterwards, the full, one step reaction was carried out and the change in temperature was taken. Once the number of moles were calculated for each reactant in each reaction, then the ΔH could be calculated. C. Observation Table 1. Reaction 1 Reaction 2 Reaction 3 Mass of solid NaOH (g) 1.503 (no solid NaOH mass) 1.726 Mass (total) of solution (g) 101.5 90.0 101.7 Final Temperature ( o C) 23.8 26.8 30.1 Initial Temperature ( o C) 20.2 21.0 21.0 ΔT 3.6 5.8 9.1 Experimental heat of reaction (q rxn ) (kJ) -1.528 -2.184 -3.872 Moles of NaOH 0.03758 0.05000 0.04315 Moles of HCl
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