Chemistry solutions help?

A solution is prepared by dissolving 150.0g od magnesium chloride in 2.0L of water. What is the osmolarity of the resulting solution?

I need help showing how to get the anwser

2 Answers

Relevance
  • mRNA
    Lv 5
    1 decade ago
    Favorite Answer

    For MgCl2 osmolarity, xc = v(MgCl2)[MgCl2]

    where v(MgCl2) = 3 (as MgCl2 dissociates into 3 species: Mg2+, 2 x Cl-)

    [MgCl2] = m(MgCl2) / V(soln)M(MgCl2)

    = (150.0) / {(2.0)(95.211)}

    = 0.7877 mol Lˉ¹

    ==> xc = (3)(0.7877)

    = 2.36 osmol Lˉ¹

    NB: This is an approximation as strictly xc = φ(X)n(X)[X], where φ is the osmotic coefficent and:

    φ = -n(H2O) ln{a(H2O)} / v(X)n(X)

    where n is moles, a is activity of water

  • 1 decade ago

    you need to work out the No. of moles of MgCl. This is done by mass/molecular mass. Then that number is divided by the volume in L. as molarity is the No. moles per L.

    I think it is better for you to do the number crunching by yourself. Or else your not really learning, just stealing my knowlege lol.

Still have questions? Get your answers by asking now.