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Science 10: Flame Test Lab Activity
Name: Block: Group Members: Date: / / Due Date: Drop Date:
The report is submitted in full, on the due date. If you are absent on the day, the report is expected to be submitted electronically. Late reports are penalized, and will not accepted past the drop date.
Criteria
Student Self Evaluation
Teacher Assessment Variables & Hypothesis: Correctly identifies independent and dependent variables, controls and develops a reasonable hypothesis based on scientific knowledge.
Flow Chart: a flow chart diagram of the procedure completed individually by each group member before the lab! Pre-Lab Questions: displays a critical understanding of the background theory.
Data, Results: Provides results & detailed observations (and diagrams where appropriate) that are presented in correctly labelled tables with descriptive, numbered titles.
Follow up Questions: Correctly identifies and explains the theory relating to the experiment and supports this with accurate observations & data.
Conclusion: Identifies and defines important concepts and principles relevant to the experiment by relating back and answering to the objective and hypothesis.
Presentation: Practical report is presented in third person past tense & in the correct format. Is written fluently and provides appropriate section headings and accurate referencing. Tables & graphs have numbered headings & descriptive titles. Data & calculations may be hand written, however the remainder of the report is to be word-processed.
Practical: Demonstrates an organized and safe approach to experimental work during the lab. Shows maturity, cooperation and leadership during laboratory work. Works collaboratively within lab group and cleans up safely and appropriately.
Results Summary /36 /
We will be doing the lab on __________________________.
In order to be ready to go, you need to complete the following sections of your lab report:
Flow Chart
Pre-Lab Questions
Data & Observations: Draw & set-up Table 1 into your lab notebook.
Flame Test Background Information & Pre-Reading (this will help with pre-lab questions)
The flame test is used to visually determine the identity of an unknown metal ion based on the color the metallic salt turns the flame of a Bunsen burner. When metals are exposed to high temperatures, electrons transition to a higher energy level (the excited state), and after, the return to the ground state while simultaneously emitting a photon. The color of this photon, in the visible spectrum, allows us to say if a metal cation is copper or potassium, for example.
Chemists began studying colored flames in the 18 th^ century and soon used the term “flame tests” to distinguish between some elements. Different elements burn with different colored flames. Although some of the flames you will be seeing will appear similar in color, their light can be resolved ( separated ) with a prism into distinctly different bands of colors on the electromagnetic spectrum ( ROYGBIV ) These bands are called atomic line spectra, and they are UNIQUE in colour and wavelength to each element.
Niels Bohr studied the line spectrum for hydrogen, and wondered what the specific line spectrum had to do with the structure of the atom. He postulated that an electron can have only specific energy values in an atom, which are called energy levels, Bohr believed that the energy levels for electrons were quantized, meaning only certain, specific energy levels were possible.
How does an electron move between energy levels? By gaining the right amount of energy, an electron can move, or undergo a transition, from one energy level to the next. By placing atoms of metals into a flame, electrons can be induced to absorb energy and jump to an excited state, a quantum jump. They then return to their ground state by emitting a photon of light ( the law of conservation of energy indicates that the photon emitted will contain the same amount of energy as that absorbed in the quantum jump ). The amount of energy in the photon determines its color : red for the lowest visible light, increasing energy through the spectrum ( ROYGBIV ) with violet being the highest energy of visible light. Photons outside the visible spectrum may also be emitted, but we can not see them.
The arrangement of electrons in an atom determines the sizes of the quantum jumps, and thus the energy and colors of the collection of photons emitted, known as the emission spectrum. In this way the emission spectrum serves as a “fingerprint” of the element to which the atoms belong. We can view the emission spectrum of colors all at once with the naked eye. It will appear to be one color, which we will carefully describe. It is also possible to view the separate colors of the emission spectrum by using a spectroscope, which bends light of different energies differently. Low energy red light, is bent the most, and high energy violet the least. This allows us to see distinct colors of the emission spectrum of a sample.
We will use the data we collect to identify a metal in an unknown salt solution. This process is the same as that used by chemical laboratories to identify the make-up of chemical combination in chemical spills, land fills, industrial sites, etc. This must be done to determine the possible threat to human health and the ecosystem due to contamination.
remaining metal compounds and the unknown(s). Make sure you are cleaning your wire loop and using the proper water beaker BEFORE testing each sample to avoid cross contamination of samples.
- Turn off the Bunsen burner. Make sure all equipment is cleaned and returned to the equipment station.
- Pour all chemical waste (including water in beakers) into the WASTE DISPOSAL FLASK provided by your teacher.
- Wash, clean up and return the equipment you have used. Spray and wipe your lab bench. Wash your hands with soap & water.
Reagent Disposal: all waste is to be collected in the WASTE DISPOSAL.
Clean Up: clean up all materials as instructed by your teacher. Glassware needs to be washed and dried for use by other students. Wipe lab bench with disinfectant and wash hands well with soap and water before you leave the lab each day.
Flow-Chart (must be completed to participate in the lab): (^) Checked by
teacher P
Pre lab Questions : ( show your teacher your answers before you begin the lab with your flow chart)
- What precautions should be taken to ensure safety during this lab? Explain. (2 marks)
- Explain the steps for lighting a Bunsen burner: (2 marks)
- What is the independent variable in this lab? (1 mark)
- What is the dependent variable in this lab? (1 mark)
- What variables are important to control to ensure a fair test? (1 mark)
- Why is it important to clean the wire loop before performing each new test? (1 mark)
- Analyze the compounds used in this experiment. What is similar about the compounds? What is different about the compounds? (2 marks)
- What happens to an electron when heat is added? (1 mark)
- What happens to an electron when heat is removed? (1 mark)
___ /12 marks
Checked by
teacher A
