Answer:
83,40 (w/w) %
Explanation:
The osmotic pressure (π) is defined as:
π = iMRT
Where i is Van't Hoff factor (3 for MgCl₂ and 2 for NaCl), M is molarity, R is gas contant (0,082atmL/molK) and T is temperature (298,15K)
iM = π / RT
iM = 0,01607mol/L
It is possible to write:
<em>3x+2y = 0,01607mol/L </em><em>(1)</em>
Where x are moles of MgCl₂ and y moles of NaCl.
<em>-M = moles of each compund because M is molarity (moles/L) and there is 1,000L-</em>
Knowing molar mass of MgCl₂ is 95,2 g/mol and for NaCl is 58,44g/mol:
<em>x×95,211 + y×58,44 = 0,5000g </em><em>(2)</em>
Replacing (2) in (1):
3x+2(0,0086 - 1,629x) = 0,01607mol/L
-0,258x = -0,00113
<em>x = 0,004380 moles of MgCl₂</em>
In grams:
0,004380 moles of MgCl₂×(95,211g/mol) = 0,417g of MgCl₂
Mass percent is:
(0,4170g of MgCl₂/0,5000g of solid) ×100 = <em>83,40 (w/w) %</em>
I hope it helps!
