2. Calculate the enthalpy change to be expected for the dissolution of NaOH ((s)
ID: 697456 • Letter: 2
Question
2. Calculate the enthalpy change to be expected for the dissolution of NaOH ((s) and (aq) mean solid and aqueous) using Hess's Law: NaOH(s)--NaOH(aq) Use the enthalpy change for NaOH-HCI pair that your class measured in this experiment and the data from the following table AH(kJ/mol 92.3 -426.8 Reaction ½H2(g) + ½Cl2(g) HCl(g) Na(s) + ½Odg) + ½H2(g) NaOH(s) Na(s) + ½Cl2(g) NaCl(s) H2(g) + ½O2(g) H2O(1) HCl(g) HCl(aq) NaCl(s) NaCl(aq) NaOH(aq) + HCI(aq) -411.1 -285.8 - 75.2 4.0 ge .7 NaCl(aq) + H2O(1) (g) - gas, (1) - liquid, (s) -solid, (aq)-aqueous Hi urExplanation / Answer
Q = mcT
Q = heat energy (Joules, J), m = mass of a substance (kg)
c = specific heat (units J/kgK), is a symbol meaning "the change in"
T = change in temperature (Kelvins, K)
Heat lost by hot water = Heat gained by water + Heat gained by calorimeter
50 x 4.184 x (98-58) = 50 x 4.184 x (58-20) + Sp ht x (58-20)
8368 = 7949 + Sp ht x (58-20)
Specific heat of Calorimeter = 11.01 J/g Deg celcius
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