5.7 Flame Emission Spectroscopy

Question 1

Describe how a spectrum is produced (3)

Answer 1

• During flame emission spectroscopy, a sample is placed in a flame. As the sample heats up, the elements in the sample transfer energy as light.
• The light passes through a spectroscope, which detects wavelengths of light and gives a line spectrum.
• The combination of wavelengths emitted by an element is called a spectrum. Different elements produce different line spectra, so you can use a spectrum to identify the elements in a sample.

Question 2

What are the two benefits of spectroscopy?

Answer 2

• Flame emission spectroscopy can be used to detect the individual wavelengths of light, allowing it to detect the prescence of multiple ions.
• Also, the intensity of the lines on the spectrum indicate the concentration of the ion. So we can use it to find the concentration of a particular ion in a solution.

Question 3

In industry and in research, chemists often use instrumental analysis (i.e. tests that use machines), such as flame emission spectroscopy, instead of conducting chemical tests. What are the advantages of doing this? (3)

Answer 3

Advantages of using machines
- Very sensitive - they can detect even the tiniest amount of substances
- Very fast - tests can be automated and data is recorded automatically
- Very accurate

Question 4

Despite the advantages of using instrumental analysis, why do some chemists still choose to use chemical tests as well?

Answer 4

Chemical tests are often cheaper and the equipment needed for them is readily available

Question 5

What does the intensity of a line spectrum indicate about a cation?

Answer 5

Its concentration