Subject: Inorganic Chemistry · Chapter: Analytical Chemistry · Topic: Analytical Chemistry – General · Exam: CSIR-NET DEC 2014 · Marks: 2 · Difficulty: Medium
The gas commonly used in generating plasma in Inductively Coupled Plasma Atomic Emission Spectroscopy (ICPAES) is:
(a)Argon
(b)Carbon dioxide
(c)Nitrous oxide
(d)hydrogen
Answer
Answer (as printed): A
Explanation
For ICP-OES and ICP_MS argon is most suitable gas to generate plasma. A number of gases cane be used to produce plasma, like $\mathrm{Ar}$, $\mathrm{Ne}$, $\mathrm{N_2}$, $\mathrm{O_2}$, $\mathrm{H_2}$, air and mixture of gases. The physical properties of the gases play a decisive role in this regard. Such important properties are ionization and dissociation energy, thermal conductivity, atomic weight and chemical reactivity. Argon belongs to the group of inert gases. It means that it does not react with the material during production of plasma. Its atomic weight - the highest among all plasma gases and it generates high kinetic energy of the plasma beam. Due to its low ionization potential argon is excellently suitable for generating the plasma beam. However, argon has a low thermal conductivity and a low thermal capacity which limits its application is some specific areas only.