1. Chemical Reactions Involved in cone. © Nuffield Foundation and the Royal Society of Chemistry. Commercial sulfuric acid is sold in several different purity grades. C6.1 What useful products can be made from acids? Dilute hydrochloric acid, HCl(aq) – see CLEAPSS Hazcard HC047a and CLEAPSS Recipe Book RB043. Practical Chemistry activities accompany Practical Physics and Practical Biology. This test helps in detection of Cl–, Br–, I–, C2O42-, and Fe2+ radicals. How do you know a reaction is taking place? The range of metals and acids tested can be extended to a teacher demonstration in the concluding part of this lesson. (SO42- and PO43-). Pure sulfuric acid has a vapor pressure of <0.001 mmHg at 25 °C and 1 mmHg at 145.8 °C, and 98% sulfuric acid has a <1 mmHg vapor pressure at 40 °C. 4. sulphuric acid is added along the wall of test tube. 1. Sulphuric Acid Test. Which metals react with sulfuric acid? It may help to develop this discussion in the concluding stages of lesson 1 by additional demonstrations of other metals and acids. Distribution of pieces of magnesium ribbon should be supervised to avoid students taking several pieces and experimenting later with igniting them. Sulfuric acid poses the following serious storage challenges: • Sulfuric acid is extremely heavy and will test the mechanical integrity of your storage tank. Reddish brown gas with pungent smell, turns FeSO. The evaporation and crystallisation stages may well be incomplete in the time available for Lesson 2. (i) Dil. As already discussed these radicals are not detected by dilute or concentrated H2S04. Le Chatelier’s principle is used to predict a colour change. This reaction is known as esterification. In particular dilute nitric acid (< 0.5 M) does produce hydrogen with moderately reactive metals such as magnesium and zinc, even though reactions are different at higher concentrations, and with other metals. Procedure Lesson 1. Place six test tubes in the test tube rack. 1. The time taken for the reaction depends on the particle size of the metal used. Hydrogen gas forms as the metals react with the acid to form salts. However, the dishes should not be allowed to dry out completely, as this spoils the quality of the crystals. (ii) Cone. This test is performed by treating small quantity of the salt with cone, sulphuric acid (2-3 ml) in a test tube. This is a resource from the Practical Chemistry project, developed by the Nuffield Foundation and the Royal Society of Chemistry. Boil the contents and add excess of ammonium molybdate solution. Explanation of differing reducing power of halides A reducing agent donates electrons. Add a 2–3 cm depth of dilute hydrochloric acid to the first three tubes, and a 2–3 cm depth of dilute sulfuric acid to the remaining three tubes. Chemical reactions involved in Potassium permanganate test . The solid is added to the acid until no more reacts and the excess solid is filtered off to produce a solution…. H2S04 and identify the gas evolved. On treating the solid nitrite with dil. Treat a pinch of the salt with dil. H2S04 to produce characteristic gases. 3. H2S04 give SO2 gas. 5. How do you know a reaction is taking place? H2S04 test. H2S04 but not with dil. Transfer the filtrate into an evaporating basin. 2. Write word equations for the reactions of i) zinc and hydrochloric acid ii) magnesium and sulfuric acid. The procedure for safely testing the evolved hydrogen gas in the test tube reactions needs to be demonstrated at a suitable point in lesson 1. If there is any doubt about the safety of this step, the teacher should first lift each beaker down onto the heatproof mat, using a thick cloth or wearing suitable thermal protection gloves, before the students add the zinc pieces. 2. On boiling, the acid may decompose to give SO2 gas. 1. The sulphuric acid manufactured in the United States, is made from sulphur and generally free from the contamination of arsenic. Deep violet vapours with pungent smell, turns starch paper blue. H2SO4 Test. Which metals react with hydrochloric acid? Before carrying out the wet tests for the analysis of cation, the salt has to be dissolved in some suitable solvent to prepare its solution. 8. A loosely inserted cork allows sufficient build-up of gas in a slow reaction to enable a successful test. H2S04 to give out CO2, H2S, SO2 and NO2 gas respectively which can be identified by certain tests. These are therefore, identified by individual tests. Perform what looks like alchemy with ordinary copper coins in this teacher demonstration. Do not heat the salt with dilute acid. To this hot acid, add about half the zinc pieces provided. Sulphites when treated with dil. Concentrated Sulphuric Acid Test This test is performed by treating small quantity of the salt with cone, sulphuric acid (2-3 ml) in a test tube. This collection of over 200 practical activities demonstrates a wide range of chemical concepts and processes. 5. Review and reflect on the skills and thinking used in carrying out investigations, and apply their learning and skills to solving problems in unfamiliar contexts. Nevertheless many students find it difficult to achieve a successful ‘pop’ test for hydrogen, so you may need to do follow-up demonstrations as well. Topic 4 - Extracting metals and equilibria, 4.3 Explain the reactivity series of metals (potassium, sodium, calcium, magnesium, aluminium, (carbon), zinc, iron, (hydrogen), copper, silver, gold) in terms of the reactivity of the metals with water and dilute acids and that these reactions show the…, 3.11 Explain the general reactions of aqueous solutions of acids with: metals, metal oxides, metal hydroxides, metal carbonates to produce salts, 3.15 Explain why, if soluble salts are prepared from an acid and an insoluble reactant: excess of the reactant is added; the excess reactant is removed; the solution remaining is only salt and water, C3.3f recall that carbonates and some metals react with acids and write balanced equations predicting products from given reactants. Add a small piece of the same metals to each of the tubes with sulfuric acid in them.