enthalpy change for a metal displacement reaction?
To determine the enthalpy change for a metal displacement reaction by adding a known mass of zinc powder to excess aqueous copper(II) sulfate solution and recording the rise in temperature.
Initial mass of weighing boat / g = 2.54
Mass of weighing boat and zinc / g = 4.57
Final mass of weighing boat / g = 2.55
Mass of zinc added / g = 2.02
Volume of aqueous CuSO4 used = 40 cm3
Temperature change / ºC = 29
- Roger the MoleLv 71 month ago
Supposing the specific heat and density of the copper solution to be the same as water:
(4.184 J/g·°C) x (40 g) x (29°C) / (2.02 g Zn / (65.380 g Zn/mol)) = 157088 J/mol
Zn(s) + CuSO4(aq) → Cu(s) + ZnSO4(aq), ΔH = -157 kJ
[The minus sign did not come from the calculations. It is the convention for exothermic processes.]