A2 Metals and Inductively Coupled Plasma Spectroscopy
1. 1.
Copper and tin are metallic elements. These metals can be mixed to form bronze. Explain briefly how the following properties are affected by mixing copper and tin: i. The electrical conductivity of the pure metals compared to the electrical conductivity of bronze ii. The hardness of the pure metals compared to the hardness of bronze
2. 2.
Explain the difference between diamagnetic and paramagnetic compounds in terms of their properties and electronic arrangements.
3. 3.
Aluminium is an important metal in modern society. It is found widely distributed over the Earth and is extracted in several stages. Explain the following: i. How is the aluminium in bauxite ore extracted and converted into pure aluminium oxide? The aluminium oxide is reduced to pure metallic aluminium by adding cryolite, melting the mixture and using electrolysis. ii. Why is cryolite added to the aluminium oxide? iii. The cathode for this process is a graphite-lined, steel tank. Explain what is used for the anodes and why they need regular replacing. iv. Write chemical equations for the electrolytic reactions at each electrode.
4. 4.
Copper is purified by electrolysis. Assuming that the copper is present in solution as
$\textsf{Cu}^\textsf{2+}$
ions, calculate the mass of pure copper that collects at the cathode during the purification process if a current of 2.00 Amps is used for 10 hours.
5. 5.
Lead is often found in wastewater from factories that manufacture electronic components, and at battery recycling plants. Its concentration can be measured by using inductively coupled plasma optical emission spectroscopy (ICP-OES). a. Explain briefly the nature of the specific plasma state involved in ICP spectroscopy. b. An ICP-OES calibration curve for Lead is shown in the graph below.. The range of values was obtained from a variety of domestic water samples. i. Determine the mass of lead ions present in
$\textsf{100 cm}^\textsf{3}$
of a solution with a concentration of
$\textsf{800 mol dm}^\textsf{3}$
. ii. Using your answer from part i. explain how you could make up suitable solutions in order to obtain this calibration curve. iii. Two samples of tap water were found to give a count rate 15 and 525 kcps respectively. Explain which sample would be more suitable to analyse using this calibration curve.
Figure 11.1