Question

Calculate the following concerning the following chemical reaction

3 Al₂O₃ (S)+AlCl₃(S) + 3NO(g) +6H₂O>>> 3Al(S) + 3NH₄CLO₄(S)

(a) what is the heat(enthalpy) of the chemical reaction?

(b) How much energy is released (or absorbed), in Kilojoules, when 15.01 g of aluminum oxide is reacted?

Answer 1

3 Al₂O₃ (S)+AlCl₃(S) + 3NO(g) +6H₂O -----> 3Al(S) + 3NH₄ClO₄(S) : ΔH = ?

ΔH = ΔH⁰_fproducts – ΔH⁰_freactants

ΔH = [(3x ΔH⁰_fAl(s) )+ (3 x ΔH⁰_f NH₄ClO₄(S) )]- [( 3 x ΔH⁰_f Al₂O₃ (S) )+ΔH⁰_f AlCl₃(S)+ (3 x ΔH⁰_{fNO (g)} )+(6xΔH⁰_f H2O(l)]

= [(3x0) + (3x(-295.31)] - [(3x(-1675.27)+(-705.63)+(3x(90.25)) +(6x(-285.83))]

= +6289.7 kJ/mol

(b) Molar mass of Al2O3 is 102 g/mol

From the balanced equation ,

3 mol = 3x102 = 306 g of Al2O3 requires 6289.7 kJ of energy

15.01 g of Al2O3 requires M kJ of energy

M = ( 15.01x6289.7) / 306

= 308.5 kJ