Preparation and Analysis for ISC 2019 Chemistry Practical

For the coming ISC 2019 Practical Examination, you will face three core questions. Each question is designed to assess your understanding and skills in chemical processes and analysis. Here, we outline the probable questions, the materials involved, and tips for preparation.

Question 1: Titration of KMnO4 against Oxalic Acid

The first question will likely be on titration, specifically involving the determination of the concentration of potassium permanganate (KMnO4) using oxalic acid (H2 C2 O4) as the analyte. This classic titration is not a common recent topic, making it a highly probable candidate for the examination.

The titration reaction is:

2MnO4- 5H2C2O4 6H → 2Mn2 10CO2 8H2O

The titration's endpoint can be observed with the disappearance of pink color due to the reduction of MnO4- to Mn2 .

Calculation Tips:

Calculate the moles of oxalic acid using its concentration and volume. Use the stoichiometry of the reaction to find the moles of KMnO4. Calculate the concentration of KMnO4 from its moles and the volume used.

Observation Table:

Observation Step Observation Titration Start Clear solution, no color change. Titration Progress Reddish-brown color gradually develops, turns pink at the endpoint. Titration End Color disappears suddenly.

Question 2: Identification of Compounds Aniline and Glucose

The second question will likely involve the identification of two compounds, C-13 and C-14, which are most probable to be aniline (C6H5NH2) and glucose (C6H12O6) based on the experiments conducted in your syllabus. Keep in mind that other compounds are also possible, so it's advisable to review all related experiments.

The identification process will involve a series of tests, such as the catalytic reduction of anilines (to produce primary amines) and the Tollens' test for glucose (a silver mirror is formed).

Observation Table:

Compound Observation and Inference Aniline Reduction with hydroxylamine to produce a red complex, silver mirror test negative. Glucose Tollens' test produces a silver mirror, iodoform test yields a yellow precipitate of triiodomethane.

Question 3: Inorganic Salt Analysis

The third question will focus on the analysis of an inorganic salt provided as C-15. The salt is quite likely to be zinc acetate (Zn(CH3COO)2). The process involves identifying and confirming one anion (acetate, CH3COO-) and one cation (zinc, Zn2 ) through confirmatory tests.

Confirmatory Tests:

Zinc Identification: Flame test gives a characteristic bluish-green color. Determination of Acetate: Add ammonium hydroxide to observe the formation of a white precipitate (Zn(OH)2).

Observation Table for Zinc Acetate:

Observation Step Observation and Inference Flame Test Bluish-green flame indicates the presence of Zn2 ions. Precipitation Test White precipitate forms with ammonium hydroxide, indicating the presence of acetate ions.

Tips for Success

Ensure that all observations are recorded accurately in a tabular format without any cuttings or overwriting in the answer booklet. Thoroughly complete all confirmatory tests and follow the experimental procedures meticulously. Prepare a list of probable compounds and practice the corresponding tests to ensure readiness.

Wishing you all the best for the ISC 2019 Chemistry Practical Examination!