3.4 Percent Composition

Question 1

What is the Law of Definite Proportions?

Answer 1

The elements in a chemical compound are always present in the same proportions by mass

Question 2

What is percent composition?

Answer 2

Percent by mass, of each element in a compound

Question 3

What is a mass spectrometer?

Answer 3

• measures MM and concentrations of atoms and molecules

Question 4

How does a mass spectrometer work?

Answer 4

• sample is injected into analyzer and vaporized by heat
• magnetic forces deflect charged particles based on size; particles are detected and analyzed

Question 5

What is combustion analysis?

Answer 5

• used to determine the composition of an unknown organic compound

Question 6

How does combustion analysis work?

Answer 6

• burns a known sample with plenty of oxygen
• uses water and carbon dioxide scrubbers to determine the percent of each atom in the compound