Editing Qualitative inorganic analysis (section)

=== 2nd analytical group of anions ===
The ''2nd group of anions'' consist of [[Chloride|Cl<sup>&minus;</sup>]], [[Bromide|Br<sup>&minus;</sup>]], [[Iodide|I<sup>&minus;</sup>]], [[Nitrate|NO{{su|b=3|p=&minus;}}]] and [[Oxalate|C{{su|b=2}}O{{su|b=4|p=2&minus;}}]]. The group reagent for Group 2 anion is concentrated sulfuric acid (H<sub>2</sub>SO<sub>4</sub>).

After addition of the acid, chlorides, bromides and iodides will form precipitates with [[silver nitrate]]. The precipitates are white, pale yellow, and yellow, respectively. The silver halides formed are completely soluble, partially soluble, or not soluble at all, respectively, in aqueous ammonia solution.

Chlorides are confirmed by the ''[[chromyl chloride]] test''. When the salt is heated with K<sub>2</sub>Cr<sub>2</sub>O<sub>7</sub> and concentrated H<sub>2</sub>SO<sub>4</sub>, red vapours of chromyl chloride (CrO<sub>2</sub>Cl<sub>2</sub>) are produced. Passing this gas through a solution of NaOH produces a yellow solution of [[sodium chromate|Na<sub>2</sub>CrO<sub>4</sub>]]. The acidified solution of Na<sub>2</sub>CrO<sub>4</sub> gives a yellow precipitate with the addition of [[lead(II) acetate|(CH<sub>3</sub>COO)<sub>2</sub>Pb]].

Bromides and iodides are confirmed by the ''layer test''. A sodium carbonate extract is made from the solution containing bromide or iodide, and [[chloroform|CHCl<sub>3</sub>]] or [[carbon disulfide|{{chem|CS|2}}]] is added to the solution, which separates into two layers: an orange colour in the {{chem|CHCl|3}} or {{chem|CS|2}} layer indicates the presence of Br<sup>&minus;</sup>, and a violet colour indicates the presence of I<sup>&minus;</sup>.

Nitrates give brown fumes with concentrated H<sub>2</sub>SO<sub>4</sub> due to formation of NO<sub>2</sub>. This is intensified upon adding copper turnings. Nitrate ion is confirmed by adding an aqueous solution of the salt to FeSO<sub>4</sub> and pouring concentrated H<sub>2</sub>SO<sub>4</sub> slowly along the sides of the test tube, which produces a brown ring around the walls of the tube, at the junction of the two liquids caused by the formation of {{chem|Fe(NO)|2+}}.<ref>{{cite book
| title = University Chemistry, Volume 1
| author = C. Parameshwara Murthy
| publisher = New Age International
| year = 2008
| isbn = 978-81-224-0742-6
| page = 133
}}</ref>

Upon treatment with concentrated sulfuric acid, oxalates yield colourless CO<sub>2</sub> and CO gases. These gases burn with a bluish flame and turn lime water milky. Oxalates also decolourise KMnO<sub>4</sub> and give a white precipitate with CaCl<sub>2</sub>.