springnet rusting compatible

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Rusting Teresa, Winnie, Jaime and Haley

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7/28/2019 Springnet Rusting Compatible

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Rusting

Teresa, Winnie, Jaime and Haley

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Definition

Rust is formed by the reaction of iron andoxygen in the presence of water or air

moisture forming hydrated iron(III) oxides.Rusting is the corrosion of iron and readilyoccurs in the alloy steel. The formation of areddish brown flakes which loosely adheres

to the iron is called rust.

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Theory of Rusting

This is an electrochemical processinvolving an anode, an electrolyte anda cathode. When metal corrodes, theelectrolyte provides oxygen to theanode. As oxygen reacts with themetal, electrons are liberated. Whenthey flow through the electrolyte to

the cathode, the metal of the anodedisappears, swept away by theelectrical flow or converted into metalcations in a form of rust.

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How is rust formed?

• Fe is oxidized to Fe2+

Pit developed on the surface• Oxygen is reduced to hydroxide ions

(impurity)

• Water acts as the electrolyte of the

reaction• Electrons flow from pit to impurity

• Iron (II) hydroxide is formed to undergo

oxidation forming hydrated (III) oxide 

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Factors that effect rate of rusting

• Purity of the iron• Stress intensity

• Electrolyte composition

• Oxygen concentration

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Equation of reaction

1. 2Fe(s) + 2H2O(l) + O2(g) ==> 2Fe2+(aq) + 4OH-(aq)

2. Fe2+(aq) + 2OH-(aq) ==> Fe(OH)2(s)

3. Fe(OH)2(s) =O2=> Fe(OH)3(s)

4. Fe(OH)3(s) =dehydrates==> Fe2O3.nH2O(s) or rust

The chemical formula for rust is Fe2O3.nH2O

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12 Principles of Green Chemistry

1. Prevention

2. Atom economy

3. Less hazardous chemical syntheses

4. Designing safer chemicals5. Safer solvents and auxiliaries

6. Design for energy efficiency

7. Use of renewable feedstock

8. Reduce derivatives

9. Catalysis10. Design for degradation

11. Real-time analysis for pollution prevention

12. Inherently safer chemistry for accident prevention

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Equipment Market Price

• Magnesium strips (RM120 per kilo)• Zinc strips (RM40 per kilo)

• Copper strips (RM 160 per kilo)

• Chromium strips (RM 100 per kilo)

• Petroleum jelly (RM20 per kilo)

• Plastic covers (RM10 per kilo)

• Copper sulphate and copper strips

(RM40 per set)

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Rusting in a steel nail

Steel is an alloy made of iron and carbon. The carbon atoms in steelgreatly increase the strength of themetal. They prevent the iron atoms inthe crystal lattice from slipping over one

another.Steel is widely used in the

manufacture of cars,

white goods and the

construction industry

because it is much

stronger than iron.

The carbon atoms in steel

however, greatly decrease 

the ability of iron to resist

corrosion.

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Methods for Preventing Rusting

• Galvanization

• Cathodic Prevention• Coatings and Paintings

• Electro plating

Grease• Tinning

• Alloy formation

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Galvanization

The process of applying a thin layer of zinc coating to steel oriron to prevent rusting. The most common type of galvanization

is hot-dip galvanizing.

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Cathodic Prevention

This is a technique used to control the corrosion of an iron or

steel by using a sacrificial anode of an electrochemical cell.

This is done by connecting the iron (cathode) to a more active

metal which corrodes more easily.

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Coatings and Paintings

By using oil paints, it

prevents water and/or

oxygen  coming into

contact with the iron.

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Electroplating

• Plating with a less reactive metal – it prevents the iron from

coming into contact with water and oxygen.

• Plating with a more reactive metal –

prevents contact withwater and oxygen and slows down rate of corrosion even

when the coating is damaged.

Zn(s) + Fe2+(aq) -----> Zn2+

(aq) + Fe(s) 

Metals used in electroplating:

• Nickel

• Chromium

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Tinning

• This is the process where a thin layer of 

thin is coated over the iron object. The

tin acts as an inert barrier which isimpermeable to steel and oxygen/water.

• The tin forms a thin oxide layer,

preventing further corrosion.

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This is where iron is converted 

into an alloy such as stainless

steel by fusing it with carbon,

chromium and nickel in adefinite proportion to prevent

corrosion. This allows an

impermeable oxide layer on

the iron surface preventingrusting.

Alloy Formation

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Aim

To come up with the best method

of prevention of rusting for atrampoline following the 12

principles of green chemistry in

the required budget.

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Prediction

• The nail wrapped in magnesium will rust the least as its

electrons are transferred on to the iron nail, therefore

causing the magnesium to rust instead of the iron.

• Vice versa, the nail wrapped in copper will rust the most.

The more reactive metal would then transfer its electrons,

increasing the rate of rusting.

• Nails wrapped in grease, Vaseline or paint would work

depending on the efficiency of its coating. If gaps are

present, it would cause the nail to be exposed to oxygen

and water, therefore causing the nail to rust.

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Method1. Prepare 21 test tubes and 3 test tube racks (7 test tubes for each testtube rack) and label them.

2. Select 18 nails which do not show any signs of rusting and clean themthoroughly with cleaning solution and dry them.

3. Wrap 3 iron nails in each type of protection - copper, magnesium, zinc,paint, oil, petroleum jelly. Leave three nails untouched.

4. Add 4cm³ of either hydrochloric acid, distilled water or salt water intoone test tube each

5. Leave it for a while and add Potassium Hexacyanoferrate into each testtube as the corrosion indicator.

6. Leave it for a few days before getting final result.

7. Take the nails out of their respected test tubes.

8. Scrape off the coating9. Judge whether it has rusted by the state of the iron nail and the colour of 

the potassium hexacyanaferrate.

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Dependent and independent variables

Dependent variables:

• The conditions of the iron nails after the experiment

Independent variables:

• Types of liquid the iron nails were in: (distilled water, salt water,hydrochloric acid)

• Materials used to prevent the nails from rusting

Constant variables:

• Identical nails (same size, same type)

• Volume of reactants (5cm3)

• Duration of the experiment

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Results

Method Normal PetroleumJelly

Grease Paint Magnesium Zinc Copper

Distilled

Water

Rusted No rust Rusted Rusted No rust No rust Rusted

Salt Water Rusted No rust Rusted Rusted Rusted No rust Rusted

Hydrochloric

acid

Rusted No rust Rusted Rusted Rusted No rust Rusted

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Petroleum Jelly

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Conclusion

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THANK YOU.

Jaime, Teresa, Winnie and Haley