What mass of each gas is present in a 1.15 −l sample of this mixture at 25.0 ∘c?

total pressure = 666/760=0.876 atm

moles gas = 0.876 x 1.10 L / 0.08206 x 298 K=0.0394

moles N2 / 0.0394 = 330/ 666

moles N2 =0.0195

mass N2 = 0.0195 x 28.0134 g/mol= 0.546 g

moles O2 / 0.0394 = 126/666

moles O2 = 0.00745

mass O2 = 0.00745 x 32 g/mol=0.239 g

moles He/ 0.0394 = 210/ 666

moles He = 0.0124

mass He = 0.0124 x 4 g/mol=0.0497 g

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.