When 1.07E-1 g of Zn(s) combines with 5.64E1 mL of HCl(aq) in a coffee cup calorimeter, all of the zinc reacts, which increases the temperature of the HCl solution from 2.32E1 °C to 2.48E1 °C:
Zn(s) + 2HCl(aq) → ZnCl_2(aq) + H_2(g)
Calculate the enthalpy change of the reaction ΔH°rxn in J/mol. (Assume the volume of the solution doesn't change, density of the solution is 1.00 g/mL and the specific heat capacity of solution is 4.184 J/g°C; the calorimetry constant is assumed to be negligible.)
2. When 2.00 g of calcium metal reacts with 100.00 g of 1.00 M HCl in a coffee-cup calorimeter, the temperature rises from 18.1ºC to 66.8ºC. The heat capacity of the calorimeter apparatus is 131 J/K. Calculate ∆H (in kJ) for the reaction:
Ca(s) + 2HCl(aq) → CaCl2(aq) + H2(g)
Assume the specific heat of the solution is 4.18 J/K∙g.
[Hint: the solution contains all the reactants.]
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