Set up a Hess's law cycle, and use the following information to calculate ΔH°f for aqueous nitiric acid, HNO3(aq). You will need to use fractional coefficients for some equations. 3 NO2(g) + H2O(l) → 2 HNO3(aq) + NO(g) ΔH° = -137.3 kJ 2 NO(g) + O2(g) → 2 NO2(g) ΔH° = -116.2 kJ 4 NH3(g) + 5 O2(g) → 4 NO (g) + 6 H2O(l) ΔH° = -1165.2 kJ NH3(g) ΔH°f = -46.1 kJ/mol H2O(l) ΔH°f = -285.8 kJ/mol

Video transcript

Hi everyone here we have a question asking us to determine the entropy of the reaction. Using Hess's law. Iron sulfide plus five halves, oxygen forms iron oxide plus two sulfur oxide. Given the following data. So let's go through each of these. So we have iron plus two sulfur forms iron sulfate and its entropy is negative 178.2 kg joules per mole. So we need to reverse that to match our reaction. So that is 178 point to kill jules Permal. And then we have iron plus half oxygen forms iron oxide and its entropy is negative 272.0 kg joules per mole. And we're just going to keep that one the same. So that will be negative, 272 zero kg Permal. And lastly we have sulfur plus oxygen forms sulfur dioxide And it's info p is negative, 296.8 kg joules per mole. And we need to multiply by that by two to match our reaction. So that will be negative .6 kg per mole. So now we have to add this all up to get our entropy. So that's going to equal 178 points to kill jewels per mole plus - zero killed jules Permal plus -593 . Killed Jules, Caramel. And that equals negative .4 Kill Jules Permal. And that is our final answer. Thank you for watching. Bye