Question

A macromolecule is added at a concentration of 18 g L−1 to water at a temperature of 10°C. If the resulting osmotic pressure of this solution is found to be equal to 12 mmHg, estimate the molecular weight of the macromolecule in grams per mole

Answer 1

Answer: 26138g/mol

Step-by-step explanation:

`\pi =CRT`

`\pi` = osmotic pressure = 12 mmHg =
`(1)/(760)* 12=0.016` atm (760 mmHg= 1atm)

C= concentration in Molarity

R= solution constant = 0.0821 Latm/Kmol

T= temperature =
`10^0C=(10+273)K=283K`

For the given solution: 18 g of macromolecule is dissolved to make 1 L of solution.

`Molarity=\frac{\text{Mass of solute}* 1000}{\text{Molar mass of solute}* \text{volume of solution in ml}}`

`C=(18* 1000)/(M* 1000ml)=(18)/(M)`

`0.016=(18)/(M)* 0.0821* 283}`

`M=26138g/mol`

The molecular weight of the macromolecule in grams per mole is 26138.