25
QuizMultiple Choice

Chemical Reactions and Limiting Reactants — Test

Question 25 • Chemistry

Which step would help a student find the molecular formula of a compound from the empirical formula?

Answer
A
Divide the subscripts by the ratio of the compound's molar mass to the empirical formula's mass.
B
Add the ratio of the compound's molar mass to the empirical formula's mass to the subscripts.
C
Multiply the subscripts in the empirical formula by the ratio of the compound's molar mass to the empirical formula's mass.
D
Subtract the ratio of the compound's molar mass to the empirical formula's mass from the subscripts.

Explanation

Find the ratio of the compound’s molar mass to the empirical formula mass. This ratio tells you how many empirical formula units make up one molecule, so multiply every subscript in the empirical formula by that ratio. Therefore, the correct choice is “Multiply the subscripts in the empirical formula by the ratio.”

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