The movement of particles from a less crowded area to a more crowded area requires what

Use the standard enthalpies of formation for the reactants and products to solve for the δhrxn for the following reaction. (the δhf of c2h4 is 52.26 kj/mol, co2 is -393.509 kj/mol, and h2o is -241.818 kj.) c2h4 (g) + 3o2(g) 2co2 (g) + 2h2o(g) δhrxn = the reaction is .

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation:

An unknown substance is a white solid at room temperature and has a melting point of 78 °c. which of the following substances is most likely to be the identity of the unknown sample? a. naphthalene, a molecular solid with the formula c10h8 b. silica, a network solid held together by covalent bonds with the formula sio2 c. calcium chloride, an ionic compound with the formula cacl2 d. water, an molecular compound with the formula h2o