calculate the empirical formula for each natural flavor based on its elemental mass percent composition:?

a. methyl butyrate (component of apple taste and smell):

C 58.80%, H 9.87%, O 31.33%

b, vanillin (responsible for the taste and smell of vanilla):

C 63.15%, H 5.30%, O 31.55%

explain, please!

thank you!

2 Answers

  • Generally: divide the mass percent by the molar masses to get the formula.

    a: C – 58.8/12 = 4.9, H – 9.87/1 = 9.87, O – 31.33/16 = 1.96

    Then divide by the smallest amount to get a ratio

    C – 4.9/1.96 = 2.5, H – 9.87/1.96 = 5.0, O – 1.0

    Then multiply to get whole numbers (here with 2) and you get C5H10O2

    If you do the same for vanillin (try it out!), you’ll get C8H8O3.

  • The ratio of the subscripts in the empirical formula are equal to the mole ratio of each element! I let the total mass of the sample = 100 grams, so the % = mass of each element. Moles = mass ÷ molar mass 1) methyl butyrate (component of apple taste and smell): C58.80 H9.87 O31.33. Moles of C = 58.80 ÷ 12= 4.9 Moles of H = 9.87 ÷ 1 = 9.87 Moles of O = 31.33 ÷ 16= 1.96 Divide each by the smallest number of moles. C = 4.9 ÷ 1.96 = 2.5 H = 9.87 ÷ 1.96 = 5.04 O = 1 C2.5 H5O1 double each subscript to have whole numbers C5 H10O2 Use the same procedure below 2)glucose (a source of energy and metabolic intermediate): C40.00 H6.71 O53.29. Answer = C1H2O1

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