In Example 3.15, the empirical formula of a compound extracted from tobacco was calculated to be C₅H₇N. In a separate experiment, the molar mass of this compound is found to be 162 g/mol. Calculate the molecular formula.

Strategy

The molecular formula is determined from the empirical formula by dividing the molar mass found in the experiment by the molar mass of the empirical formula and multiplying the subscripts of the empirical formula by the resultant whole number.

Example 3.15

Calculate the empirical formula of a compound extracted from tobacco. Chemical analysis shows that this substance contains 74.0% carbon , 8.70% hydrogen , and 17.3% nitrogen.

Example 3.14

Analysis of a 0.330-g sample of a compound shows that it contains 0.226 g chromium and 0.104 g oxygen. What is the empirical formula?

Transcribed Image Text:

Mass composition Molar mass of elements Moles of each element Divide by smallest number Empirical formula as fraction Multiply to eliminate fraction Empirical formula