Question

A solution containing 15.13 g of glucose in 100.0 g of water was found to freeze at -1.29 ⁰C with a 1.86 ⁰C/m. what is the molar mass of glucose. Please show how to solve this, not just the answer.

Answer 1

As we know the freezing point depression depends on the concentration of solution, the mathematical expression is

i= Vant Hoff factor and for glucose it is 1.

cryoscopic constant , which depends only on the properties of solvent.

(given)

Calculation of temperature change

Calculation of mole (b)

By using the law of freezing point depression

Calculation the molecular weight.

As we know

Here given mass is 15.13 g

number of mole is 0.69 moles

now apply the above rule

Hence the molar mass of glucose is 219.27 g/mol.