0620 CHEMISTRY : METALS Learning Objectives Do you still remember the general physical properties of metals & non metals? General means usual or typical [physical properties that metals and non metals have] Task Create a comparison table for the general properties of metals & non metals, which include the following physical properties : ● Thermal conductivity ● Electrical conductivity ● Malleability & ductility ● Melting points & boiling points General physical properties of metals vs non metals Textbook pg : 280 Learning Objectives Reaction of metals & dilute acids ● Video :”Reactivitity of Metals with HCl - Qualitative Lab”MrGrodskiChemistry ● Task : ○ Write your observations for each reaction of metals with hydrochloric acid in the video. ■ The metals are : Tin, Iron, Magnesium, Copper, Zinc and Calcium Reaction of metals & dilute acids ● What are your observations? ● Effervescence in tubes where metal react with the acid. ● Ca & Mg react very strongly with dilute hydrochloric acids ● Zn & Fe react less strongly with dilute hydrochloric acids ● Sn & Cu does not react with dilute hydrochloric acids Reaction of metals & water ● Video :”Reactivitity of Metals with water - Qualitative Lab”MrGrodskiChemistry ● Task : ○ Write your observations for each reaction of metals with hydrochloric acid in the video. ■ The metals are : Tin, Iron, Magnesium, Copper, Zinc and Calcium ○ Why phenolphthalein was added to the water? Reaction of metals & water ● What are your observations? ● Effervescence in tubes where metal react with water. ● Phenolphthalein changes colour from colourless to pink. ● Suggest what is produced in the reaction that caused the phenolphthalein to change colour. Reaction of metals & water However, in the video it seems liked that only Ca & Mg reacts with water ; Mg reacts very slowly Zn & Fe seemed like it does not react with water. What if react with another form of water? Reaction of metals & water (steam) Mg, Al, Zn, Fe react with steam much more vigorously. Watch a video that show the reaction between Mg and Steam Task : ● Write the observation of the reaction ● Write the chemical equation of the reaction Reaction of metals & water (steam) Zn & Fe react the same way : Heat the metals & pass steam over the heated metals What can you say about the products produced? When metals react with cold water When metals react with steam Metal hydroxide is produced + Hydrogen gas Metal oxide is produced + Hydrogen gas Reaction of metals & oxygen ● What is the % of gases in air? https://www.thesciencehive.co.uk/gases-in-the-atmosphere-gcse Reaction of metals & oxygen ● Among the gases in the air, the most reactive would be oxygen. ● Metals reacts readily with oxygen to form oxides Reaction of metals & oxygen i.e. Mg burns in air / O2 to form MgO. ● Burns brightly ● Produced MgO ; white solid Reaction of metals & oxygen i.e. Fe (burns in air/ O2) or reacts slowly with air + water to from hydrated iron (III) oxide (a.k.a rust) Reaction of metals & oxygen i.e. Al reacts readily with oxygen in air. Forming a layer of Al2O3 on its surface. Hence “hiding” the metal’s reactivity. This layer of oxide creates a protective barrier that prevent against corrosion. https://chemistryklipz.files.wordpress.com/2017/01/igcse-extraction-and-uses-of-metals.pdf Reaction of metals with acids, oxygen and water. Textbook pg: 281 Reactivity series Learning Objectives Metal reactivity series Reactions of metals with water/steam and acids can be used to compare the reactivity. Displacement reaction Can be used to precisely placed a particular metal in the reactivity series. Key points in displacement reaction : ● More reactive metal displaces a less reactive metals from solutions of salts of the less reactive metals. ● More reactive metals tends to form cations ● Displacement reaction is an example of a REDOX reaction. Displacement reaction Discussion ● What is the chemical equation of the reaction? ● What is the ionic equation of the reaction? ● How is this reaction is a REDOX reaction? Discuss in terms of : ○ Electrons ○ Oxidation number ○ Which species is the oxidation / reducing agent? Metal reactivity series H position was based on the reaction of metals with water & dilute acids. ● Position of C was based on the metals extraction. ● Al is a reactive metal. It appears to react slowly because of the Al2O3 layer on the surface of the metal. ○ The Al2O3 layer act as a protective layer; slowing the reaction Textbook pg: 305 ● Metals Extraction Learning Objectives Learning Objectives Learning Objectives Learning Objectives
