GC quick question

[mg777]

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this is from topscore, i get a different answer than theirs, and im almost sure im doing this osmotic pressure problem right.

If you have a solution of 1L H2O and 234g NaCl, what is the osmotic pressure at STP? (R= .1 L* atm/mol*k)

A. 89.54
B.109.2
C.146.61 ATM
D.218.4
E. 234

I get 109.2 B, but the asnwer says its D. 218.4. someone want to give this problem a quick try.

 

[SloppyJoe]

The answer is doubled because NaCl breaks on into Na+ and Cl-, and so the molarity doubles to in effect.

 

[mg777]

oh i see. thanks. does that happen only with ions? Would u multiply by 3 if the molecule was MgCl2?

 

[SloppyJoe]

It only happens w/ soluble ions. So you are correct in multiplying by 3 when it is MgCl2