[Rexosaurus]

I've tried this problem a couple times, but can't seem to come up with the proper answer.

Question:
Consumer products express concentrations in mg/volume or g/volume because the general public isn't familiar with molarity.
a) A medium-sized (296 mL) cup of coffee contains 0.10 g caffeine, C₈H₁₀N₄O₂. Express this concentration in molarity.


My work:
0.10 g C₈H₁₀N₄O₂/296 mL X 1mol/74g X 1 mL/10^-3 L

I'm not sure where to go from here. I keep getting 4.56, which the textbook says is wrong. Is anyone able to point me in the right direction?

[chenbeier]

Check die molar mass of caffeine. 74 g/mol is to low.

[Rexosaurus]

Thank you!

[MNIO]

excellent setup... it's good to see you using factor label method.. also watch your sig figs

  0.10g caffeine       1 mol caffeine         1000mL
 ----------------- x --------------------- x ----------- = ___ M
     298mL              194.19g caffeine         1 L

this is all multiplication and division... the result is limited to what?