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PSEB SS Chemistry study materials
PSEB SS Chemistry study resources

PSEB SS Chemistry: PSEB Senior Secondary Chemistry - Practical

PSEB SS Chemistry · Work through your exam, one topic at a time.

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PSEB Senior Secondary Chemistry - Practical

What the practical paper tests

The PSEB Senior Secondary Chemistry practical domain assesses laboratory technique and record work: volumetric analysis (acid–base and redox titrations), systematic salt analysis for anions and cations, functional-group tests on organic compounds, and simple preparations or pH measurements. The examiner looks for correct apparatus use, reliable observations, a neat tabulated record, and a viva explanation of why each reagent is added.

Core rules

  • Volumetric analysis: rinse the burette with the titrant and the pipette with the solution it will deliver; read the bottom of the meniscus at eye level; use concordant readings within 0.1 mL.
  • Indicator choice: phenolphthalein for strong acid–strong base and weak acid–strong base; methyl orange for strong acid–weak base.
  • Salt analysis: test anions first on the original solution, then cations by group reagents - dilute HCl (Group I), H2S in acidic medium (Group II), NH4OH (Group III), H2S in alkaline medium (Group IV), ammonium carbonate (Group V). Confirm with flame tests or specific precipitates.
  • Organic tests: FeCl3 for phenols, Tollens' and Fehling's for aldehydes, iodoform for methyl ketones or ethanol, Lucas test for alcohol classes.

Worked example

25.0 mL of oxalic acid solution is titrated against NaOH and requires 20.0 mL. If the oxalic acid is 0.050 M, find the molarity of NaOH. H2C2O4 + 2NaOH → Na2C2O4 + 2H2O. Moles oxalic acid = 0.0250 × 0.050 = 1.25 × 10−3 mol. NaOH moles = 2 × 1.25 × 10−3 = 2.50 × 10−3 mol. Molarity = 2.50 × 10−3 / 0.0200 = 0.125 M. So the NaOH solution is 0.125 M.

Traps that cost marks

  • Adding group reagents out of order in salt analysis, which precipitates the wrong group and hides the cation.
  • Not acidifying the solution before H2S for Group II.
  • Recording a single titre instead of concordant readings.
  • Confusing Fehling's colour change (blue to red precipitate) with Tollens' silver mirror.
  • Forgetting to state the confirmatory test for an anion after the preliminary test.