Virtual Flame Test Lab.pdf, High school final essays of Chemistry

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Flame Test Lab Objectives

1. Observe the characteristics of the atomic emission

spectra of certain elements

2. Diagram the observed spectra

3. Identify an unknown element based on the spectra

Background: Each element in the Periodic Table has a specific number of electrons in specific energy levels. When atoms of any element absorb energy, electrons move from lower to higher energy levels called the excited state. As these electrons fall back into their original energy levels (ground state), the excess energy is released as electromagnetic radiation (visible light portion).

Background: Colors of light are commonly referred to in terms of their wavelength, so the following is used to calculate the energy in Joules.

∆E = hc ∆E = the difference of energy between the two energy Λ h = Plank’s constant (6.626 x 10 -34^ J·sec) c = speed of light 3.00 x 10 8 m/s Λ = the wavelength of light in meters (need to convert)

Background: Table 1 lists the wavelengths associated with each of the colors in the visible spectrum. The representative wavelengths are used as benchmarks for each color. A color of yellow – orange may be estimated at 585 depending on the degree of yellow or orange that is seen. When obtaining a wavelength for an observed color, estimate wavelength and express as a single value rather than as a range.

Pre-Lab Questions:

1. Explain in detail why elements emit colors when

heated. (include electron discussion)

Pre-Lab Questions:

2. Convert 565 nanometers into meters

Pre-Lab Questions:

4. Find (google) and insert an image of the entire

electromagnetic spectrum and color of the enlarged

visible spectrum portion.

Pre-Lab Questions:

5. What types of waves represent the highest

energy on the EM spectrum? The lowest

energy?.

Pre-Lab Questions:

7. Using Table 1, estimate the representative

wavelength in nm if you see a mostly yellow but

some orange color emitted.

Pre-Lab Questions:

8. What are the 6 metals that are being tested in

the lab? Watch this video to get your known

samples

Metal Salt Name of Metal ONLY

Color of the Flame Representative Wavelength in nanometers (see Reference Data Table)

Strontium Chloride

Lithium Chloride

Copper II Chloride

Calcium Chloride

Potassium Chloride

Sodium Chloride

Unknown

Data Table #

Metal and Color of the Flame

Λ (nm) Λ (m) ΔE (J)

Unknown

Data Table #

Write the electron configuration for Magnesium in the ground state

Answer:

Rank the metals in order of increasing energy emitted as their electrons returned to the ground

state

Answer:

Predict the color of the flame if the following materials were heated in the flame. Explain your

predictions.

1. Cupric Nitrate, Cu(NO 3 ) (^2)
2. Sodium Sulfate, Na 2 SO (^4)
3. Potassium Nitrate, KNO (^3)

Answer: