Question

please answer all 4 questions. i don't need a long answer. please explain them briefly and correctly. Thank you in advance.

1. What does the term qualitative analysis mean?

2. The confirmatory reactions that identify nitrate and nitrite both produce brown NO2 gas. What criterion will you use to determine which anion produced the gas?

3. The confirmation reaction for the halides involves the addition of chlorine water. Describe how you will know which, if any, of the anions is present.

4. A student added calcium ion, Ca+2 to an aqueous solution and observed formation of a precipitate. Addition of HNO3 had no effect on the precipitate. What anion was present in the original solution? Explain your answer.

Answer 1

Q.1: In qualitative analysis we determine the chemical composition of a cmpound by detecting the type of ions present in that compound. During qualitative analysis we make several physical and chemical tests that are specific to a particular group and ion. During the physical and chemical test we identify the compound by observing the appearance, color change, precipitate formation, different types of gas formation etc.

Q.2: Both nitrite and nitrate ion give brown fume of NO2 gas when treated with H2SO4.

Whoever when it is prduced by nitrate ion(NO₃^-), the brown fume intensifies when copper turning is added. Also if it is prduced by nitrate ion(NO₃^-), it will give brown ring test, because this test is only given by nitrate ion(NO₃^-).

In brown ring test we add FeSO4 to the test tube. A brown ring is formed when we contineously add con.H2SO4.

Q.4: Anions like CO₃^2- and SO₄^2- form precipitation with Ca2+ due to frmation of CaCO3 and CaSO4 respectively. However CaSO4 doesn't react with HNO3. Hence the anion is sulphate ion.