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.

Strategy

The empirical formula is calculated as in Example 3.14 using the percentages as grams in a 100-g sample.

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?

Strategy

The strategy is outlined in the following diagram.

The mass composition values are converted to moles using periodic table information and the molar values converted to whole numbers.

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