Freezing Clothing Moths
Chemistry Question! Please help?
A solution of 2.00 g of para-dichlorobenzene (moth repellent) in 50.0 g of cyclohexane, 1.05 freezes º C. What is the molar mass of this substance?
dT = Kf x molality, where dT is the lower melting temperature changes, Kp is the constant molar freezing point for cylohexane and p-dichlorobenzene molality = mol / kg cyclohexane. pure cyclohexane freezes at 6.4 C and has a value of 20.2 K, C / mole (of chemistry tables.) The freezing point has been reduced from 6.4 to 1.05 molality = 5.35 = C dT / Kf = 5.35 C / 20.2 C / mole = 0.265 mole molality = p-dichlorobenzene mol / kg cyclohexane. mol p-dichlorobenzene cyclohexane kg molality = = 0.265 x 0.050 = 0.0132 mol x molar mass = g / mol = 2.00 g / 0.0132 mol = 151 g / mol.
Cloth moth death by tech duster
