The addition of 100 g of a compound B to 750 g of CCl 4 lowered the freezing poi

Question

1. The      addition of 100 g of a compound B to 750 g of CCl4 lowered the      freezing point of a solvent by 10.5 K. Calculate the molar mass of the      compound if the Kf, CCl4=30K kg mol-1.

PLEASE SHOW ALL RELEVENT EQUATIONS AND WORK THE EQUATION MATHEMATICALLY SO I CAN SEE HOW IT IS DONE! Thank you! PLEASE SHOW ALL RELEVENT EQUATIONS AND WORK THE EQUATION MATHEMATICALLY SO I CAN SEE HOW IT IS DONE! Thank you! The addition of 100 g of a compound B to 750 g of CCl4 lowered the freezing point of a solvent by 10.5 K. Calculate the molar mass of the compound if the Kf, CCl4=30K kg mol-1.

Explanation / Answer

Freezing point depression = Delta Tf = 10.5 K

Molality = Delta Tf/Kf

= 10.5/30 = 0.35m


Mass of CCl4 = 750 g = 0.75 kg

Moles of compound = molality x mass of CCl4 in kg

= 0.35 x 0.75 = 0.2625 mol


Mass of compound = 100 g

Molar mass of compound = mass/moles of compound

= 100/0.2625

= 380.95 g/mol = 381 g/mol

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