Question

The standard enthalpy of formation (ΔH∘f) is the enthalpy change that occurs when exactly 1 mol of a compound is formed from its constituent elements under standard conditions. The standard conditions are 1 atm pressure, a temperature of 25 ∘C , and all the species present at a concentration of 1 M . A "standard enthalpies of formation table" containing ΔH∘f values might look something like this: Substance ΔH∘f H(g) 218 kJ/mol H2(g) 0 kJ/mol Ba(s) 0 kJ/mol Ba2+(aq) −538.4 kJ/mol C(g) 71 kJ/mol C(s) 0 kJ/mol N(g) 473 kJ/mol O2(g) 0 kJ/mol O(g) 249 kJ/mol S2(g) 129 kJ/mol

What is the balanced chemical equation for the reaction used to calculate ΔH∘f of BaCO3(s)?

If fractional coefficients are required, enter them as a fraction (i.e. 1/3). Indicate the physical states using the abbreviation (s), (l), or (g) for solid, liquid, or gas, respectively without indicating allotropes. Use (aq) for aqueous solution.

Answer 1

BaCO3 (s) ;

balanced chemical equation :

Ba (s)   + C (s) + 3/2 O₂ (g)   ------------> BaCO₃ (s)

Explanation :

the standard states of reactants :

Ba (s) , C (s) , O2 (g)