Hess’ Law:Work to be done:Find enthalpy change by measuring temperature change of a reaction. Chemicals and apparatus: Thermometer Scale Isolator NaOH, solid NaOH, 0.50M solution Acetic acid, 0.50M and 0.25M Lab: Reaction 1) The temperature of 200ml water that I poured into the isolator was 23.0°C. To that I added 1.97g solid NaOH and let the reaction take place. After a while I measured the temperature to 24.9°C à rT = 1.9°C. The number of mole …showed first 75 words of 318 total…

…showed last 75 words of 318 total…I can use the same c in all three cases H = 0.84 T (c = 4.2, m = 0.200g) rH1 = 1.596 rH2 = 2.1 rH3 = 3.78 According to Hess’ Law you should be able to calculate the enthalpy change for a reaction which is the sum of two (or more) reactions with known enthalpy change, so:NaOH(s) à NaOH(aq) (1) NaOH(aq) + HCl à NaCl + H2O (2) NaOH(s) + HCl à NaCl + H2O (3) (3) - (2) = (1) and we can also see that rH3 - rH2 » rH1