Given the following reactions

n2 (g) + o2 (g) → 2no (g) δh = +180.7 kj

2n2o (g) → o2 (g) + 2n2 (g) δh = -163.2 kj

the enthalpy of reaction for

2n2o (g) → 2no (g) + n2 (g)

is kj.

Ican determine the molar mass of an element by looking on the under the atomic mass for the element. for example the molar mass of phosphorus is 30.974 grams/mole. avogadro’s number tells me the amount of representative particles in 1 mole of any substance. this means 12.011 gram sample of carbon and a 32.0 gram sample of sulfur have the same number of atoms.