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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: daisydesi on October 23, 2019, 06:37:04 PM

Title: Solving for osmolarity confusion
Post by: daisydesi on October 23, 2019, 06:37:04 PM

What is the osmolarity of a solution that contains 4.00% (m/v) NaCl (fm = 58.44 g/mole) and 3.00% (m/v) glucose (fm = 180.18 g/mole)?

a) 8.80 osmol
b) 11.0 osmol
c) 1.54 osmol
d) 0.851 osmol
e) 1.37 osmol
f) 7.00 osmol
g) 3.08 osmol

i attempted it already but I had gotten it wrong twice.
(4.00%moles/ 100 Liter) x (2 osmol/1 mole) = .08 osmol/Liter
(3.00 moles glucose/ 100 L glucose) x (1 osmol/ 1 mole ) = .03 osmol/ Liter
.08 (osmol/liter) + .03 (osmol/liter) = 11.00 osmol

I could be missing something because answer B wasn't correct

Title: Re: Solving for osmolarity confusion
Post by: AWK on October 24, 2019, 02:47:21 AM

Calculate correctly concentrations of both compound in 1 liter.

Title: Re: Solving for osmolarity confusion
Post by: mjc123 on October 24, 2019, 05:31:04 AM

4% m/v doesn't mean 4% moles/100 liter (a meaningless expression anyway). m/v means mass per volume. 4% m/v means 4 g solute per 100 mL solution