Carbon, hydrogen and ethane each burn exothermically in an excess of air. ahⓡ =-393.7 kj mol. c(s) + o2(g) → co2(g) h2(g) + % o2(g) → h20(1) czha(g) + 302() → 2co2(g) + 2h2o(1) ah®=-285.9 kj mol ah =-1411.0 kj moll. use the data to calculate the standard enthalpy change of formation, ah in kj mol'', of ethene at 298 k 2c(s) + 2h2(g) → c2h4(g)

Pauling and lewis questioned the extreme definitions of bonds. they wondered if bonds might be described somewhere in between the two extremes (covalent and ionic). on the basis of experimental data, pauling confirmed that bonds could be ionic, covalent, and for those, in between, exhibit a degree of ionic character. he theorized that the major factor was how strongly the atoms in the bond attracted the electrons. pauling called this factor - the tendency of an atom to attract electrons in a bond.

The last few miles of the marathon are the most difficult for heather, her hair plastered to her head, sweat clinging to her arms, and her legs already feeling as if they had nothing left, just dead weight. after grabbing a cup of ice water, she feels the ice cubes smash against her nose as she gulps some cool refreshment and keeps on running. in these last few miles, the breeze kicks up and she finally feels some coolness against her skin. drips of sweat, once clinging to her forehead, now spill down, and heather feels more pain as the sweat flows into her eyes. which of the following is the most likely reason why the ice struck heather’s nose when she took a drink? a) water can function as a solvent. b) water can store large amounts of heat. c) water can moderate temperatures through evaporative cooling. d) the density of water decreases when it freezes. e) water has a cohesive nature. sweat remained on heather’s forehead and arms because of the a) high salt content of sweat b) cohesive nature of water c) ability of water to moderate heat d) high evaporative cooling effect of water e) ability of water to act as a solvent

Find the mass, in grams, of 5.00*10^23 molecules of f2