Many hydrocarbons exist as structural isomers, which are compounds that have the same molecular formula but different structures. For example, both butane and isobutane have the same molecular formula: C4H10- Calculate the mole percent of isobutane in an equilibrium mixture at 25° C, given that the standard Gibbs energy of formation of butane is -15.9 kJ/mol and that of isobutane is -18.0 kJ/mol. Does your result support the notion that straight-chain hydrocarbons (that is, hydrocarbons in which the C atoms are joined in a line) are less stable than branched-chain hydrocarbons?