Qualitative Analysis of Inorganic Salts

Cu2+

Ni2+

pale green

<p>colourless, odourless</p> Signup and view all the answers

<p>Cl—</p> Signup and view all the answers

<p>Ca2+</p> Signup and view all the answers

<p>NO3—</p> Signup and view all the answers

<p>NH4+</p> Signup and view all the answers

<p>H2S</p> Signup and view all the answers

<p>distilled water</p> Signup and view all the answers

<p>neutralised</p> Signup and view all the answers

<p>Br2</p> Signup and view all the answers

<p>Fe3+</p> Signup and view all the answers

<p>Fe3+</p> Signup and view all the answers

<p>Zn2+</p> Signup and view all the answers

<p>Zn2+</p> Signup and view all the answers

<p>Mn2+</p> Signup and view all the answers

<p>Mn2+</p> Signup and view all the answers

<p>Ni2+</p> Signup and view all the answers

<p>greenish</p> Signup and view all the answers

<p>NH4Cl</p> Signup and view all the answers

<p>Ca2+</p> Signup and view all the answers

<p>acidic</p> Signup and view all the answers

<p>tabular</p> Signup and view all the answers

<p>Manganese</p> Signup and view all the answers

<p>precipitate</p> Signup and view all the answers

<p>NH4OH</p> Signup and view all the answers

<p>sink</p> Signup and view all the answers

<p>CO32—</p> Signup and view all the answers

<p>curd-like white (AgCl)</p> Signup and view all the answers

<p>FeSO4</p> Signup and view all the answers

<p>con.H2SO4</p> Signup and view all the answers

<p>BaSO4</p> Signup and view all the answers

<p>HCl</p> Signup and view all the answers

<p>lead</p> Signup and view all the answers

<p>SO42—</p> Signup and view all the answers

<p>ammonia</p> Signup and view all the answers

<p>fumes</p> Signup and view all the answers

<p>NaOH</p> Signup and view all the answers

<p>4ml</p> Signup and view all the answers

<p>PbCl2</p> Signup and view all the answers

<p>Copper sulphide</p> Signup and view all the answers

<p>Al(OH)3</p> Signup and view all the answers

<p>HCl</p> Signup and view all the answers

A confirmatory test for the presence of carbonate ions (CO32-) in a solution. It involves passing carbon dioxide gas through clear limewater, which turns milky due to the formation of calcium carbonate.

A confirmatory test for chloride ions (Cl-) in a solution. It involves adding dilute nitric acid (HNO3) followed by silver nitrate (AgNO3) solution to the sample. A thick, curd-like white precipitate of silver chloride (AgCl) forms, which dissolves in excess ammonium hydroxide (NH4OH) solution.

This test confirms the presence of nitrate ions (NO3-) in a solution. It involves treating the sample with dilute sulfuric acid (H2SO4), adding freshly prepared ferrous sulfate (FeSO4) solution, and agitating the mixture well. A thin dark brown ring forms at the junction between the reaction mixture and concentrated sulfuric acid (H2SO4) added dropwise along the inside wall of the test tube.

This test confirms the presence of sulfate ions (SO42-) in a solution. It involves acidifying the sample with dilute hydrochloric acid (HCl) followed by the addition of barium chloride (BaCl2) solution. It forms a white precipitate of barium sulfate (BaSO4), which is insoluble in concentrated hydrochloric acid (HCl).

This test also confirms the presence of sulfate ions (SO42-) in a solution. It involves acidifying the sample with dilute acetic acid followed by the addition of lead acetate [(CH3COO)2Pb] solution. It forms a white precipitate of lead sulfate (PbSO4), which is soluble in ammonium acetate [CH3COONH4] solution.

A chemical test used to identify the presence of specific cations (positively charged ions) in a sample by observing the color of the flame produced when the sample is heated.

A chemical test that involves adding dilute hydrochloric acid (HCl) to a sample, which produces carbon dioxide gas (CO2) if carbonate ions (CO32-) are present. This gas causes effervescence, the bubbling of a liquid.

A chemical test where concentrated sulfuric acid (H2SO4) is added to a sample. If chloride ions (Cl-) are present, a white, pungent gas (hydrogen chloride, HCl) is produced, creating dense white fumes, especially noticeable when a bottle of ammonia solution (NH4OH) is held near the test tube.

A chemical test where concentrated sulfuric acid (H2SO4) is added to a sample and the mixture is heated. If nitrate ions (NO3-) are present, reddish-brown nitrogen dioxide gas (NO2) is produced when the mixture is boiled with copper turnings.

The color of the sample can often provide initial clues about the presence of certain cations, especially transition metals.

A systematic procedure for identifying the specific anion and cation present in an unknown inorganic salt.

The use of concentrated hydrochloric acid (HCl) to make a paste of the sample before performing the flame test.

It is crucial to note whether the sample is heated or warmed during the anion tests, as this impacts the reaction and the type of gas produced.

A test to confirm the presence of ammonium ions (NH4+) in a sample. The solid salt sample is treated with sodium hydroxide (NaOH) solution, producing ammonia gas (NH3) with a distinct pungent smell. The gas can be further confirmed by releasing it near the mouth of a test tube containing concentrated hydrochloric acid (HCl) which produces dense white fumes due to the formation of ammonium chloride (NH4Cl).

A test to confirm the presence of ammonium ions (NH4+) in a sample. The solid sample is treated with NaOH solution followed by Nessler's reagent. A brown precipitate is formed, indicating the presence of ammonium ions.

A deep blue color formed by the reaction of Fe3+ ions with Potassium ferrocyanide (K4[Fe(CN)6]).

A method used to separate cations into different groups based on their solubility in water and their reaction with specific reagents.

A solution that dissolves in distilled water to create a transparent solution. The concentration can be adjusted by dissolving more salt in the water.

A blood red color formed by the reaction of Fe3+ ions with Potassium thiocyanate (KCNS).

The process of combining a small amount of a sample (usually a pinch) with a solvent (like distilled water, dilute HCl, or dilute HNO3). The solubility of the sample determines the choice of solvent.

A white precipitate of Zn(OH)2 forms when NaOH is added to a solution containing Zn2+ ions. This precipitate dissolves in excess NaOH, forming the soluble tetrahydroxozincate(II) ion [Zn(OH)4]2-.

A greenish-bluish white precipitate of [Zn2[Fe(CN)6]] forms when Potassium ferrocyanide (K4[Fe(CN)6]) is added to a solution containing Zn2+ ions.

The first step in inter-group separation of cations. A sample solution is treated with dilute hydrochloric acid (HCl). The formation of a white precipitate indicates the presence of group I cations (lead (Pb), mercury (Hg), and silver (Ag)).

A white precipitate of Mn(OH)2 forms when NaOH is added to a solution containing Mn2+ ions. This precipitate quickly oxidizes to brown MnO2 in air.

The second step in inter-group separation of cations. After group I separation, hydrogen sulfide gas (H2S) is passed through the solution. The formation of a black precipitate indicates the presence of group II cations (copper (Cu), lead (Pb), cadmium (Cd), bismuth (Bi), mercury (Hg), and arsenic (As)).

A purple color is formed by the reaction of Mn2+ ions with sodium bismuthate (NaBiO3) in the presence of nitric acid (HNO3). The purple color changes to brown on standing.

The third step in inter-group separation of cations. About 2 ml of a salt solution is treated with 2 ml of a saturated ammonium chloride (NH4Cl) solution. The formation of a gelatinous white precipitate indicates the presence of group III cations. These cations include aluminum (Al) and iron (Fe) which form insoluble hydroxides in the presence of excess ammonia.

A scarlet red precipitate is formed by the reaction of Ni2+ ions with dimethylglyoxime in the presence of excess ammonia (NH4OH).

Most nickel salts are greenish in color.

A chemical test used to identify the presence of calcium ions (Ca2+) in a solution.

A chemical reagent used to test for calcium ions (Ca2+) in a solution. It reacts with calcium ions to form a white precipitate.

A chemical reagent used in the calcium ion test and other chemical tests. It helps to create a neutral environment for the reaction to occur.

The process of separating a solid from a liquid by spinning the mixture at high speed. This forces the denser solid to settle at the bottom.

A substance that is formed during a chemical reaction and settles to the bottom of the container. It may dissolve in excess solvent.

The ability of a solid to dissolve in a liquid. Some solids dissolve well in certain liquids but not in others.

A chemical test used to identify and confirm the presence of a specific ion in a solution. The test produces a specific observable result.

A liquid that is neither acidic nor alkaline. It has a neutral pH.

Nessler's reagent is a sensitive test for ammonium ions (NH4+). However, certain other ions like zinc (Zn2+) and manganese (Mn2+) can also give a false positive, producing a brown precipitate. Therefore, it's crucial to first confirm the presence of ammonium ions using a separate test, like the NaOH test, before employing Nessler's reagent.

To confirm the presence of cations, you can use true solutions prepared from the precipitates formed during inter-group separation. Choose an appropriate solvent to dissolve the precipitate and create a solution for further testing.

When using sodium bismuthate solution, always shake the bottle vigorously before dispensing any reagent. This is because sodium bismuthate is sparingly soluble in water, and shaking ensures that a homogeneous mixture, rather than just the supernatant water, is transferred to the test tube.

If the second confirmatory test for nickel (Ni2+) fails, it might be due to the use of weak bromine water (Br2). Ensure the bromine water is fresh and strong for accurate results.

When confirming the presence of chloride ions (Cl-) with calcium ions (Ca2+), neutralization is mandatory. This is because calcium chloride (CaCl2) exhibits acidic properties. Neutralization ensures a neutral environment for accurate identification.