Acompound contains only carbon, hydrogen, nitrogen, and oxygen. combustion of 0.157 g of the compound produced 0.213 g of co2 and 0.0310 g of h2o. in an- other experiment, 0.103 g of the compound produced 0.0230 g of nh3. what is the empirical formula of the compound? hint: combustion involves reacting with ex- cess o2. assume that all the carbon ends up in co2 and all the hydrogen ends up in h2o. also assume that all the nitrogen ends up in the nh3 in the second experiment.

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.