48 Chapter

Apuntes

•Colour scale in chemistry Each group will prepare 100 mL of hydrated copper(II) sulphate solution with a molar mass M = 250 g/mol. They will share their solutions to create a colour scale using test tubes. The teacher will then provide an unknown solution whose concentration must be determined. •Preparation of solutions and concentration calculations Group data: Concentrations (mol/L): 1.10^-3, 2.10^-3, 4.10^-3, 8.10^-3, 2.10^-2, 5.10^-2. 1. Indicate the calculations made before weighing. 2. Provide a framework for the concentration of the unknown, justifying your reasoning. •Activity 1: Simulation "Prepare a solution by dissolution" Use the simulation at http://www.ostralo.net/3_animations/swf/solution.swf to verify your preparation calculations. How does the amount of matter change when preparing a larger volume of solution? •Dilution of a stock solution 2.1. Principle of dilution In laboratories, it is often easier to dilute solutions to lower concentrations rather than directly dissolving small amounts of solute. When the mass of solute is too small for direct weighing, dilution is used. Accurate measurement tools like volumetric pipettes, flasks, an...