# Molar mass

## Main Question or Discussion Point

To determine the molar mass of a certain protein, 1.00E-3 grams of the protein was dissolved in enough water to make a 1.00 mL solution. The osmotic pressure of this solution was found to be 1.12 torr at 25.0C. Calculate the molar mass of the protein.

Gokul43201
Staff Emeritus
Gold Member
Yes ? And what do you want us to do ?

physicsss said:
To determine the molar mass of a certain protein, 1.00E-3 grams of the protein was dissolved in enough water to make a 1.00 mL solution. The osmotic pressure of this solution was found to be 1.12 torr at 25.0C. Calculate the molar mass of the protein.
I assume you want help in working out the molar mass. Where are your attempts first???

I tried using this equation: p = i M R T, but I have no idea what i is.

ShawnD
physicsss said:
I tried using this equation: p = i M R T, but I have no idea what i is.
i = moles of stand-alone stuff per mole of stuff (for lack of better words). for example, i for sulphuric acid is 3. i for potassium chloride is 2. i for acetic acid is 1 (weak acids do not dissociate).

Do you know what it is for protein?

ShawnD