Final Chemistry Practical Examination

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by Sugeeth Jayaraj Samala Augustine (talk)

How will the exam be held?

The exam will be for 30 Marks. All questions are mandatory to answer. ⁠Bring your own Match box, Lab Coat, Waste Cloth and Exam pad if required.

Section A

There will be one or two salts that’ll be given to you. You will be expected to do the required tests and write down the entire “procedure, observations, inferences” table and results section.

The Salts that are a part of the portions are:

1. Strontium Nitrate [ $Sr(NO_3)_2$ ]

2. Barium Nitrate [ $Ba(NO_3)_2$ ]

3. Zinc Sulphate [ $ZnSO_4$ ]

4. Calcium Chloride [ $CaCl_2$ ]

Section B (Viva Voce)

You will be asked questions related to Salt Analysis, the four salts, and their related concepts in Chemistry,

Must Read: THE CBSE LAB MANUAL on Qualitative Salt Analysis, Theory (from the Practicals Manual), Viva Voce (from the Practicals Manual), the Chart of all Salt Analysis Tests (from the Practicals Manual)

Don’t trust the record for factually accurate information. But, take a look at it for the order of writing the required salts analysis. And read up the related processes in detail from the Chem Manual.

• ⁠You are requested to memorise the Chemical Reactions given in the Manual for the Viva Voce to be held.

• ⁠You are expected to express good knowledge of the salt analysis process from all fronts during the Viva.

• ⁠_OPTIONAL_: In case you have any doubts regarding the Chemistry Practicals, please clarify them with mam.

Suggestions: Related concepts in Chemistry (from the Class 11 Chem Book)

Reference Material

CBSE Lab Manual - Qualitative Salt Analysis.pdf

Some points to note

Points to note for tomorrow’s exam:-

• Reporting time for students of Batch 1 at the Lab: 8:30 AM (So you have to be in school by 8:20 AM and be in a line outside by 8:25 AM)

Basic Radical Tests (Chlorine - Confirmatory)

The order of adding the compounds is really important.

1. Test for Chlorine - Nitric Acid Test

$$Salt \; solution + Conc. \; HNO_3 + AgNO_3 \longrightarrow\ White \; ppt \; formation.$$

1. Test for Chlorine - Evolution of Gas test. Heat the following reactants in a test tube for the product to form.

$$Salt \; solution + MnO_2 + Conc. \; H_2 SO_4 \longrightarrow Cl_2 \; gas \; evolved.$$

1. Another Confirmatory Test for Chlorine:

$$Salt \; Solution + Solid \; K_2 Cr_2 O_7 + Conc. \; H_2 SO_4 \longrightarrow Red \; Vapour + \mathbf{Resultant \; Solution}$$

Now take the resulting solution and do this reaction.

$$\mathbf{Resultant} + NaOH + dil. \; CH_3COO + Lead \; Acetate \longrightarrow Yellow \; PPT$$

Acid Radical (Calcium)

The order of the tests matter.

1. The Calcium Flame Test - Take some salt on a spatula and burn it. If the flame colour is brick red, it’s probably Calcium

2. The Conc. HCl Test - Take some salt in a watch glass, mix it with conc. HCl. Then, burn it with the help of a glass rod.

3. Group Separation Tests:

   The tests are in the observation note. However, for the Group 5 test, the order of adding the compounds matter. The correct order is: (not given in note)

$$Salt \; solution + [NH_4]_2 CO_3 + NH_4 Cl + NH_4 OH \longrightarrow White \; PPT \; formed + \mathbf{Resultant \; Solution}$$

1. Confirmatory Test:

$$\mathbf{Resultant} + Ammonium \; Orlate \longrightarrow White \; ppt$$

Thus, the evolution of White ppt confirms the presence of Ca.

…for $CaCl_2$

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