A chemist uses the apparatus shown in Figure 3.4 to determine the composition of a compound made up of only carbon, hydrogen, and oxygen. During combustion of a 0.1000-g sample , the mass of the first trap (collecting H₂O) increased by 0.0928 g H₂O and the mass of the second trap (collecting CO₂) increased by 0.228 g CO₂. (Note that it is possible for the sum of the masses of the H₂O and CO₂ to be greater than the mass of the starting sample because some of the oxygen in the products comes from the added O₂.) Calculate the mass and mass percentage of each element in the 0.1000-g sample.

Figure 3.4

Strategy

The formulas of water and carbon dioxide, coupled with the periodic table, allow the conversion of mass of each compound to mass of the two respective elements by using the following sequence: mass compound → moles compound; moles compound → moles of element; moles element → grams element. Oxygen is calculated by difference from the mass of C and H, and the total mass of the sample.

Transcribed Image Text:

0₂ Sample Furnace CaCl₂ NaOH