If one mole of caffeine has a mass of 194.19 g and you drink an average of two servings of this drink a day, how many caffeine molecules do you ingest in one year

The standard cup of coffee sold in coffee shops have a serving size of 6 ounces. Since there are 28.3495 g in 1 oz, that is equivalent to 170.097 grams. Since you drink two servings, the total mass is 170.097*2 = 340.194 g. Using the molar mass (194.19 g/mol) and the Avogadro's number (6.022*10²³ molecules/mol):

340.194 g caffeine (1 mol/194.19 g) (6.022*10²³ molecules/mol) = 1.055*10²⁴ molecules