Corrosion S2 Chemistry Classifying chemicals and chemical reactions

Learning outcomesSuccess criteria Understand what is meant by ‘corrosion’. You can define ‘corrosion’. Understand what is meant by ‘rusting’. You can define ‘rusting’. Know what chemicals are required for rusting to happen. You can name the two chemicals. Know how the rate of rusting can be changed. You can state three ways of increasing the rate of rusting. Know how to use an indicator to detect rusting. You can name the indicator used to detect rusting. You can state its starting and finishing colours.

Do all substances rust? Only metals can rust. Some metals rust and some don’t. It depends on their position in the Reactivity Series. Alloys don’t rust.

When nails go rusty they will get heavier. When nails go rusty they get lighter. When nails get rusty they stay the same weight.

Definitions Corrosion “a chemical reaction which involves the surface of a metal changing from an element into a compound.” Rusting “the corrosion of iron.”

A metal corrodes when the surface atoms react to form a compound. Metals corrode fastest when they are exposed to. Different metals corrode at different rates: corrodes very quickly. LO:I know what is meant by corrosion of a metal. sodium air hardly corrodes at all. silver An uncorroded metal is in appearance. A corroded metal is in appearance. shiny dull Corrosion is also an example of.oxidation

When nails get wet they go rusty. They will not rust if they are completely under water. They will not rust if you keep them cold. They will go rusty more quickly if they touch other nails.

oil water nail drying agent LO:I know what causes corrosion. Experiment water only water & oxygen oxygen only

The iron only rusts when and are present. LO:I know what causes corrosion. wateroxygen Only the corrosion of is called rusting. The rusting of iron can be speeded up by: Adding salt. iron Adding acid. Heating it up. Result:

LO:I know how to test for rusting. The presence of rusting is detected using. indicator: rust Rust indicator changes colour from to in the presence of rust. yellowblue rust indicator

Preventing corrosion S2 Chemistry Classifying chemicals and chemical reactions

Learning outcomesSuccess criteria Understand how iron can be protected from rusting. You can state eight different methods which can protect iron from rusting. You can explain why each method is effective as a form of protection. You can state which metal is used in galvanising.

Brainstorm How many different ways that we use to try and prevent rusting can you think of?

Painting

Greasing

Plastic coating

Cathodic Protection

Electroplating

Galvanising

Tin Plating

If the iron atoms are constantly provided with surplus they can’t corrode and form ions. LO:Understand how iron can be protected from rusting. electrons battery Cathodic protection: electricity (Iron is connected to the negative terminal (cathode) of a power supply.) - Car bodywork is connected to the negative terminal of the. - Oilrig platforms are connected to the negative terminal of the generator.

Experiment: LO:Understand how iron can be protected from rusting.

- Iron will not be able to form. LO:Understand how iron can be protected from rusting. higher Sacrificial protection: ions - A metal in the electrochemical series will give electrons to iron. - Magnesium will. instead. e.g. iron and magnesium Mg 2e - + Mg 2+ corrode

- A metal in the electrochemical series will take electrons from iron. - Copper will not be able to form. LO:Understand how iron can be protected from rusting. lower HOWEVER: ions - Iron will faster than normal. e.g. iron and copper Fe 2e - + Fe 2+ corrode

Learning outcomesSuccess criteria Understand how iron can be protected from rusting. You can state eight different methods which can protect iron from rusting. You can explain why each method is effective as a form of protection. You can state which metal is used in galvanising.