Question 1: Explain the scientific principle behind flame tests for identifying metal ions.

Answer: When metal ions are heated in a flame, their electrons gain energy and jump to higher energy levels. As they return to lower levels, they emit light of characteristic colours specific to each metal ion.

Question 2: List three safety precautions to consider when performing a flame test in the laboratory.

Answer: Wear safety goggles, handle chemicals with tongs, and perform tests in a well-ventilated area away from flammable materials.

Question 1: What is the characteristic flame colour produced by the sodium ion?

Answer: Yellow

Question 2: Which metal ion produces a lilac or purple flame?

Answer: Potassium

Question 3: Multiple Choice: Which of the following ions produces a brick-red flame?

Answer: Strontium

Question 1: Describe the key steps involved in performing a flame test to identify a metal ion in a salt sample.

Answer: First, clean a platinum or nichrome wire by dipping it in hydrochloric acid and then rinsing with distilled water. Dip the wire into the salt sample and hold it in a blue Bunsen burner flame. Observe the colour produced by the flame, which indicates the metal ion present. Repeat with other samples for comparison.

Question 2: A student observes a flame that is bright orange. Which metal ion is most likely present?

Answer: Calcium

Question 3: A flame test is performed on a sample suspected to contain copper ions. The observed flame colour is green. Explain why this colour confirms the presence of copper.

Answer: Copper ions emit a characteristic green flame due to the electronic transitions of electrons in copper atoms when heated. The specific wavelength of light emitted is unique to copper, confirming its presence.

Question 1: Calculate the energy (in joules) emitted when a photon of light with a wavelength of 480 nm is released during a flame test. Use the formula: E = hc/λ, where h = 6.626 x 10^-34 Js, c = 3.00 x 10^8 m/s, and λ is in meters.

Answer: E = (6.626 x 10^-34 Js)(3.00 x 10^8 m/s) / (480 x 10^-9 m) = 4.14 x 10^-19 Joules

Question 2: Explain how flame tests are used in industry, providing one specific example.

Answer: Flame tests are used in the metal industry to verify the presence of specific metal ions in ores or alloys, such as identifying calcium or magnesium in cement production.

Question 3: Describe one limitation of flame tests for identifying metal ions and suggest an alternative method.

Answer: Flame tests can be inaccurate if multiple ions produce similar colours or if impurities are present. An alternative is using spectroscopy, which provides more precise identification.