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Calculatethe grammolecularmass of thefollowing NH_(3) |
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Answer» Solution :(i) Osmotic pressure: It is the pressure of the solution column that can prevent the entry of solvent molecules throgh a semi-permeable membrane, when the solution and the solvent are separted by the same. It is denoted by `pi.` Its unit is mm Hg or atmosphere. We KNOW that, `pi= CRT` where `pi` is the osmotic pressure and R is the gas constant `jjpi = (n _(2))/(V) RT` where V is volume of solution per litre containing `n _(2)` moles of solute. `piV= (W_(2))/(M _(2)) RT` `M _(2) =(W_(2) RT)/(piV)` By the above relation molar mass of solute can be calculated. (ii) The osmotic pressure method has the ADVANTAGE over other methods as pressure measurement is around the room temperature and molarity of the solution is USED instead or molality. The technique of osmotic pressure for determination of molar mass of solutes is particularly useful for biomolecules as they are GENERALLY not stable at higher temperature and polymers have poor solubility. |
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