Question

Calculate the standard enthalpy change for the following chemical reaction involving solutions:2HNO3(aq) + Ba(OH)2(aq) → Ba(NO3)2(aq) + 2H2O(l)Given the following information:ΔHf° [HNO3(aq)] = -207.5 kJ/molΔHf° [Ba(OH)2(aq)] = -994.0 kJ/molΔHf° [Ba(NO3)2(aq)] = -537.5 kJ/mol

Answer 1

To calculate the standard enthalpy change for the given reaction, we can use Hess's Law, which states that the enthalpy change of a reaction is the sum of the enthalpy changes of the products minus the sum of the enthalpy changes of the reactants.The reaction is:2HNO3 aq  + Ba OH 2 aq   Ba NO3 2 aq  + 2H2O l The standard enthalpy change for this reaction  H  can be calculated using the following equation:H = [Hf products ] - [Hf reactants ]Hf values are given for each compound:Hf [HNO3 aq ] = -207.5 kJ/molHf [Ba OH 2 aq ] = -994.0 kJ/molHf [Ba NO3 2 aq ] = -537.5 kJ/molHf [H2O l ] = -285.8 kJ/mol  this value is a standard value for the formation of liquid water Now, we can plug these values into the equation:H = [1   -537.5  + 2   -285.8 ] - [2   -207.5  + 1   -994.0 ]H = [-537.5 - 571.6] - [-415.0 - 994.0]H = [-1109.1] - [-1409.0]H = 299.9 kJThe standard enthalpy change for the given reaction is 299.9 kJ.