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

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

Question 2: Describe the mechanism by which metal ions produce colour in a flame test.

Answer: Metal ions absorb energy from the flame, causing their electrons to move to higher energy levels. When electrons return to lower levels, they emit light at specific wavelengths, producing characteristic colours.

Question 1: If a sodium ion emits a wavelength of 589 nm during a flame test, calculate the energy of the photon emitted. Use the formula E = hc/λ, where h = 6.626 x 10^-34 Js, c = 3.00 x 10^8 m/s.

Answer: E = (6.626 x 10^-34 Js)(3.00 x 10^8 m/s) / (589 x 10^-9 m) = 3.37 x 10^-19 Joules

Question 2: A potassium ion produces a violet flame with a wavelength of 766 nm. Calculate the energy of the emitted photon in joules.

Answer: E = (6.626 x 10^-34 Js)(3.00 x 10^8 m/s) / (766 x 10^-9 m) = 2.59 x 10^-19 Joules

Question 1: List three safety precautions that should be taken when performing a flame test in the laboratory.

Answer: Wear safety goggles, handle Bunsen burners carefully, and avoid inhaling fumes or inhaling vapours from chemicals.

Question 2: Identify three variables that could affect the colour produced in a flame test and how they might influence the result.

Answer: Variables include the concentration of the metal ion, the type of flame used (luminous or non-luminous), and the cleanliness of the sample; these factors can alter the intensity and clarity of the colour observed.

Question 1: A student tests a metal salt solution and observes a red flame. The emission spectrum shows a prominent line at 656 nm. Which metal ion is most likely present? Justify your answer.

Answer: The metal ion is most likely hydrogen (H) or possibly lithium, but given the context of flame tests and emission at 656 nm, it strongly suggests the presence of hydrogen emission lines. However, in typical flame tests for metal ions, a red flame is characteristic of lithium ions. Since the emission at 656 nm matches the hydrogen alpha line, it indicates hydrogen is present, but if considering metal ions, lithium is the most probable.

Question 1: Explain how flame test analysis is used in industry to identify metal contaminants in raw materials.

Answer: In industry, flame tests are used to quickly identify the presence of specific metal ions in raw materials or products. For example, in quality control, a flame test can detect unwanted metal contaminants in mineral ores or alloys by observing characteristic colours. This helps ensure material purity and consistency. The process is rapid, cost-effective, and often used alongside other analytical techniques for confirmation.

Question 2: Describe a modern technological application that relies on the principles of flame emission spectroscopy, which is related to flame tests.

Answer: Flame emission spectroscopy is used in environmental monitoring to detect trace metal pollutants in water or air samples. It allows precise identification and quantification of metals like lead, cadmium, and mercury by analysing their characteristic emission lines, applying the same principles as flame tests but with more advanced instrumentation.