Question

the caffeine content in soda bottle is 63mg/ 20 fl oz, <-- labelled on the actual bottle. The calculated concentration of caffeine is 0.423 mM in the soda sample, experimentally.

how to convert mM to mg/ floz or vice versa. calculate the percent difference between experimental and actual, then determine the concentration caffeine in the soda bottle.

Answer 1

Solution :-

Caffeine molar mass =194.19 g/mol

0.423 mM * 1 M / 1000 mM = 0.000423 M

1 flOz= 29.5735 ml

20 flOz * 29.5735 ml / 1 flOz = 591 ml

591 ml / 1000 ml per L = 0.591 L                                                                                                    

0.000423 mol per L * 0.591 L = 0.00025 mol

0.00025 mol * 194.19 g/mol = 0.0487 g caffeine

So 0.0487 g * 1000 mg / 1g = 48.7 mg/ 20 flOZ

So calculated concentration is 48. 7 mg caffeine / 20 flOz

Now lets calculate the percent difference

Percent difference = (actual – calculated / actual )*100%

                                   = (48.7 mg -63 mg/63)*100%

                                   = 22.7 %

Now lets calculate the concentration in the bottle

48.7 mg/20 flOz = 0.423 mM

So

63 mg /20 flOz = ? mM

63 mg * 0.423 mM / 48.7 mg = 0.547 mM