Which numerical setup can be used to calculatethe formula mass of C9H11NO2?

Regents Chemistry Exam June 2024 Question 36

36 Which numerical setup can be used to calculate the formula mass of C9H11NO2?

(1) 9 u + 11 u + 1 u + 2 u

(2) 12 u + 1 u + 14 u + 16 u

(3) 9(6 u) + 11(1 u) + 1(7 u) + 2(8 u)

(4) 9(12 u) + 11(1 u) + 1(14 u) + 2(16 u)

Solution:

To calculate the formula mass of a molecule, we need to multiply the number of atoms of each element by the mass found on the Periodic Table. There are 9 carbon, 11 hydrogen, 1 nitrogen, and 2 oxygen atoms. The mass of carbon is 12 amu, hydrogen is 1 amu, nitrogen is 14 amu and oxygen is 16 amu. Choice 4 is the correct answer choice.

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