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Chapter 21: Problem 4

Describe two methods for determining the identity of an unknown compound that is either \(\mathrm{Li}_{2} \mathrm{CO}_{3}\) or \(\mathrm{K}_{2} \mathrm{CO}_{3}.\)

Short Answer

Expert verified
The two methods that could be used are solubility testing and flame testing. \(\mathrm{Li}_{2} \mathrm{CO}_{3}\) would display poor solubility and a red flame, while \(\mathrm{K}_{2} \mathrm{CO}_{3}\) would display high solubility and a lilac flame.

Step by step solution

01

Method 1: Solubility Test

Perform a solubility test. Dissolve a small amount of the unknown substance in distilled water and observe. Potassium carbonate (\(\mathrm{K}_{2} \mathrm{CO}_{3}\)) is highly soluble in water while lithium carbonate (\(\mathrm{Li}_{2} \mathrm{CO}_{3}\)) is poorly soluble. If the unknown substance dissolves easily, it is likely to be \(\mathrm{K}_{2} \mathrm{CO}_{3}\). If not, it's more likely to be \(\mathrm{Li}_{2} \mathrm{CO}_{3}\).
02

Method 2: Flame Test

Perform a flame test. Transfer some of the dissolved unknown substance to a fireproof loop and hold it in a Bunsen burner flame. Observe the color change of the flame. Lithium compounds give a crimson red flame while potassium compounds give a lilac flame. The color indicates which element is present.

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Most popular questions from this chapter

Write plausible chemical equations for the (a) dissolving of lead(II) oxide in nitric acid; (b) heating of \(\operatorname{snCO}_{3}(\mathrm{s}) ;\) (c) reduction of lead(II) oxide by carbon; (d) reduction of \(\mathrm{Fe}^{3+}(\mathrm{aq})\) to \(\mathrm{Fe}^{2+}(\mathrm{aq})\) by \(\mathrm{Sn}^{2+}(\mathrm{aq});\) (e) formation of lead(II) sulfate during high-temperature roasting of lead(II) sulfide.

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