Question

Calculate the standard enthalpy change for the reaction between [Co(en)2Cl2]Cl and NaNO2 to form [Co(en)2(NO2)2]Cl and NaCl, given the following information: [Co(en)2Cl2]Cl and [Co(en)2(NO2)2]Cl have a ΔHf° of -288 kJ/mol and -136 kJ/mol, respectively. The ΔHf° of NaNO2 and NaCl are -463.2 kJ/mol and -411.2 kJ/mol, respectively. Assume that the reaction is conducted at a constant pressure and temperature of 298 K.

Answer 1

To calculate the standard enthalpy change for the reaction, we can use the following formula:H reaction  =  Hf products  -  Hf reactants The reaction is:[Co en 2Cl2]Cl + NaNO2  [Co en 2 NO2 2]Cl + NaClHf values are given as:[Co en 2Cl2]Cl: -288 kJ/mol[Co en 2 NO2 2]Cl: -136 kJ/molNaNO2: -463.2 kJ/molNaCl: -411.2 kJ/molNow, we can plug these values into the formula:H reaction  =  [-136 kJ/mol] + [-411.2 kJ/mol]  -  [-288 kJ/mol] + [-463.2 kJ/mol] H reaction  =  -547.2 kJ/mol  -  -751.2 kJ/mol H reaction  = 204 kJ/molSo, the standard enthalpy change for the reaction is 204 kJ/mol.