Question 1: Explain the scientific principle behind why different metal ions produce different colours in a flame test.

Answer: Different metal ions emit characteristic wavelengths of light when their electrons are excited by heat, producing distinct flame colours due to their unique electron arrangements.

Question 1: Define a flame test and describe its purpose in chemical analysis.

Answer: A flame test is a qualitative analytical method used to identify metal ions based on the colour they produce when heated in a flame.

Question 2: What safety precautions should be followed when performing a flame test?

Answer: Wear safety goggles and a lab coat, conduct tests in a well-ventilated area or fume cupboard, and handle hot equipment with tongs.

Question 1: Identify the variable that is changed in a flame test experiment and the variable that is measured.

Answer: The variable changed is the metal salt sample (type of ion), and the measured variable is the colour of the flame.

Question 2: List two safety precautions to observe during a flame test.

Answer: Use tongs to hold metal samples and ensure the area is free of flammable materials.

Question 1: A student observes a flame colour that is bright yellow. Which metal ion is most likely present?

Answer: The metal ion is most likely sodium (Na⁺), which produces a bright yellow flame.

Question 2: A flame test on a sample produces a crimson red colour. Identify the metal ion responsible.

Answer: The metal ion is most likely lithium (Li⁺).

Question 3: A compound containing calcium produces a brick-red flame. Explain why calcium produces this colour.

Answer: Calcium ions emit a characteristic brick-red flame due to the energy released when their electrons return to lower energy levels, producing specific wavelengths of red light.

Question 1: The wavelength of the emission line for copper in a flame test is approximately 510 nm. Calculate the energy of a photon emitted at this wavelength. (Use the formula: E = hc/λ, where h = 6.626 x 10⁻³⁴ Js, c = 3.0 x 10⁸ m/s).

Answer: E = (6.626 x 10⁻³⁴ Js)(3.0 x 10⁸ m/s) / (510 x 10⁻⁹ m) = 3.90 x 10⁻¹⁹ Joules

Question 1: Describe how flame tests are used in the metal industry for quality control.

Answer: Flame tests are used to verify the presence of specific metal ions in alloys or coatings, ensuring the correct composition and quality of the product.

Question 2: Explain how understanding flame colours can help in developing new technologies such as LED lighting.

Answer: By understanding the emission spectra of different elements, scientists can design materials that emit specific colours when excited, aiding in the development of energy-efficient and colour-specific LED lighting systems.