The word molarities is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 14
Highest Scoring Words With Friends™ Plays In The Letters
Seven Letter Word Alert: (42 words)
airiest, airtime, armlets, atomise, elitism, estriol, iolites, irisate, isolate, limiter, loamier, loiters, maestro, mailers, maltier, maltose, marlite, militar, mistier, mistral, moister, morales, mortals, mortise, motlier, oiliest, realism, realist, remails, retails, saltier, siltier, similar, siriema, slatier, slimier, smartie, smilier, stromal, tailors, toilers, tramels