Answer:
Explanation:
Equation of the reaction:
CaO(s) + 2H+(aq) -----> Ca2+(aq) + H2O(g)
The ∆Hrxn would be for one mole of CaO reacted or 2 moles of H+, whichever is the limiting reactant.
Number of moles = mass ÷ molar mass
Molar mass of CaO = 40 + 16
= 56 g/mol
moles of CaO = 2.90/56
= 0.0518 mol
Number of moles = concentration × volume
moles of HCl = 400 × 10^-3 × 1.500 = 0.6 moles
Moles of HCl = moles of H+
From the equation, 1 mole of CaO reacted with 2 moles of H+ to give 1 mole of water.
To find the limiting reagent,
0.6 mole of H+/2 moles of H+ × 1 mole of CaO
= 0.3 moles of CaO(> 0.0518 moles)
So, CaO is limiting reactant.
∆H = m × Cp × ∆T
m = density × volume
= 400 × 1
= 400 g
Cp = 4.184 J/g-ºC
∆T = +6 ºC
∆H = 400 × 4.184 × 6
= 10041.6 J
Since the reaction is exothermic,
∆Hrxn = -∆H/mol(CaO)
= -10041.6/0.0518
= -193853 J
= -193.9 kJ/mol.
