NJC 2 VA _ Redox

National Junior College SH1 Chemistry 1 Content • Reacting volumes (of solutions) • Redox processes; electron transfer and/or of changes in oxidation number (oxidation state) Learning Outcomes required for H2 (9729) and H1 (8873) Chemistry: [The term relative formula mass or Mr will be used for ionic compounds] Candidates should be able to (a) Write and /or construct balanced equations; (b) Perform calculations, including use of the mole concept, involving volumes and concentrations of solutions; [when performing calculations, candidates’ answers should reflect the no. of significant figures given or asked for in the question] (c) Deduce stoichiometric relationships from calculations such as those in (b). (d) Describe and explain redox processes in terms of electron transfer and/or of changes in oxidation number (oxidation state). (e) Construct redox equations using the relevant half-equations. Volumetric Analysis & Redox All Rights Reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording or any other information storage and retrieval system, without prior permission in writing from the copyright owner. Copyright © 2023 National Junior College

National Junior College SH1 Chemistry 2 1. VOLUMETRIC ANALYSIS (TITRATION) Note: Standard solution is a solution of known concentration. The standard solution may also be placed in the conical flask, and the reactant of unknown concentration in the burette. Success Criteria: • Understand what the following terms mean: analyte; standard solution; titrant; end-point; equivalence point Volumetric analysis (or titrimetric analysis) is carried out to obtain quantitative information about chemical reactions, such as the concentration of a solution and/or establish the stoichiometry of a reaction. General overview of the titration method: 1. Pipette a portion of the solution of unknown concentration (called the analyte) into a conical flask. 2. Add a few drops of a suitable indicator into the conical flask. (Some titrations do not require any indicator) 3. Titrate the solu tion by adding a standard solution from a burette slowly, with constant swirling until a first permanent colour change is noted (this is the end-point). End-point (experimental): The point during titration at which a sudden sharp colour change (of indicator) is observed. Equivalence point (theoretical): The po int during titration at which stoichiometric amounts of the two reactants have reacted completely with one another, i.e