Do Now! Describe how aluminium can rust, and how it’s different to rusting iron (use the information found in the “Iron and Aluminium” worksheet) Aluminum is very, but is usually covered by a thin “skin” of oxide, which protects the metal underneath from attack by oxygen, water, or acids. Iron is less active, but its oxide skin is porous in water. It doesn’t protect the metal underneath from oxygen in wet conditions, and the whole of the metal eventually reacts to form the oxide.

Iron and Aluminum (continued) and revision Miss Jan

Iron rust is porous – allows oxygen to enter the metal, which allow more rusting

Rusting Aluminium? Aluminum is actually very prone to corrosion. However, aluminum corrosion is aluminum oxide, a very hard material that actually protects the aluminum from further corrosion. Aluminum oxide corrosion also looks a lot more like aluminum, so it isn't as easy to notice as rusted iron.

“How to prevent rusting” sheet Each table group read through and summarize one method of preventing rust. Then report to back to the class – report should contain: What is this method? How does it work?

Sacrificial metal To be bolted onto the hull of the boat Why is it labeled “do not paint”?

Galvanised iron Coat of zinc – prevent water or oxygen from reacting with iron

Electroplating Chrome and nickel coating

The paint stops oxygen and water from reaching the iron beneath. Method How it works Where it’s used Painting The paint stops oxygen and water from reaching the iron beneath. Cars, roofs Greasing Machinery Electroplating A coating of a metal like tin or chromium stops oxygen and water reaching the iron. Car and bike parts Galvanising A coating of zinc stops oxygen and water reaching the iron and also corrodes before the iron. Roofs, sheds Alloying Combining the iron with chromium or nickel to make stainless steel slows down rusting. Kitchen surfaces

Questions about rusting Iron oxide Iron, water, oxygen Iron + oxygen  iron oxide Brass (Cu + Zn) does not rust. Steel (99% Fe) rusts Painting provides a barrier to water and oxygen, preventing them from reacting with iron

Two sacrificial metals: magnesium and zinc Hull of ship or drilling platform, hot water heater Copper – the steel/Fe will become the sacrificial metal Zinc Zinc prevents water or oxygen from reaching iron. Also acts as sacrificial metal (will corrode before iron)

Revision Barrier activity Quiz

Quiz Give one example of the use of metals relating to each of the different physical properties. Ductile Sonorous Malleable High melting point Lustrous High electrical conductance Gold - earrings Brass – cow bells Steel – car bodies Cooking pots - steel Silver - mirror Copper – electrical wires

Name the elements represented by the following symbols. Al Fe Sn Pb Na Au S I He Cu Draw the atom diagram for Electron: Proton: Neutron: Al 27 13 13 13 27 – 13 = 14 13p 14n

Rusting Only one metal rusts. Which one is it? What is the chemical name for rust? What conditions are needed for rusting to occur? Give at least four different methods of preventing rusting and explain how each one works. Give an example of a situation in which each of these methods is used.

The paint stops oxygen and water from reaching the iron beneath. Method How it works Where it’s used Painting The paint stops oxygen and water from reaching the iron beneath. Cars, roofs Greasing Machinery Electroplating A coating of a metal like tin or chromium stops oxygen and water reaching the iron. Car and bike parts Galvanising A coating of zinc stops oxygen and water reaching the iron and also corrodes before the iron. Roofs, sheds Alloying Combining the iron with chromium or nickel to make stainless steel slows down rusting. Kitchen surfaces

The reaction of metals with water What is the general word equation for the reaction of metal with water? Metal + water  metal hydroxide + hydrogen Write the word equation for the reaction of calcium with water. Calcium + water  calcium hydroxide + hydrogen How do you test for the gas produced in the reaction in Q3? Pop test – put flame near collected gas, if hydrogen was present, a squeaky pop should be heard.

The reaction of metals with acid What is the general word equation for the reaction of metal with acid? metal + acid  salt + hydrogen Write the word equation for the reaction of zinc with hydrochloric acid. Zinc + hydrochloric acid  Zinc chloride + hydrogen

The reaction of metals with oxygen Write the general word equation for the reaction of metals with oxygen. Metal + oxygen  metal oxide Write the word equation for the reaction of magnesium with oxygen. Magnesium + oxygen  Magnesium oxide

Magnesium reacts slowly with hot water and doesn’t react with cold water. Calcium reacts rapidly with hot water and slowly with cold water. Sodium explodes in hot water and reacts rapidly with cold water. Which of these three metals is the most active chemically? Which metal is the least active? Sodium Magnesium

Think about it… How could you make zinc sulfate from zinc metal? Could you make copper sulfate in the same way? Explain your answer. Why would it not be a good idea to store vinegar (dilute acetic acid) in aluminium cans? Car batteries contain dilute sulphuric acid. Why are battery cases made of plastic rather than steel? By reacting Zn with dilute sulfuric acid No Acid in vinegar would react with Al and make holes in can As above

Atomic alphabet Make an “Atomic alphabet” Ask your partner to guess the words For example, “My name starts with the letter A, and I am the smallest particle of an element.”