$**$

De$.$ter.mine the. com.po$.$si$.$tions an$.$d $*$ qua.nt$.$iti.es of ga$.$s an$.$d li$.$quid whe.n $1$ Ib mo$.$le of a mix.ture o$.$f $20$ mo$.$le per.cent meth.ane an$.$d $30$ per.cent et$.$hane is brou.ght to equi.libri.um a$.$t $250$ psia a$.$nd $-20$F$.***$

$*$Wha$.$t wa$.$s th$.$e eff.ect of chan.ging the com.po$.$siti.on of t$.$he mixt.ure?.