Experiment 5: Metals and Some Aspects of Corrosion Flashcards
hydrated iron(III) oxide, Fe2O3*xH2O – formed slowly at the surface of iron when it exposed to the damp air.
rust
- a redox reaction that takes place between iron and oxygen to form hydrated iron(III) oxide and this is a slow reaction
- metal is oxidized to form an oxide layer on the surface, the metal atoms lose electrons to form positive ions
rusting/corrosion
used as a catalyst to make corrosion faster
agar agar
turns pink in the region where oxygen is taking electrons producing OH^-
phenolphthalein indicator
used to detect the presence of Fe^2+ forms a blue or green or blue green color in the region where oxidation of iron is taking place
potassium hexacyanoferrate
The rate of rusting of iron decreases if the iron (Fe) in contact with any of these metals:
K, Na, Ca, Mg, Al and Zn.
The rate of rusting of iron increases if the iron (Fe) in contact with any of these metals:
a strong electrolyte (salt and acid) is present.
Sn, Pb, Cu, Hg, Ag and Au.
protect iron surface, prevent from contacting with air and water
painting
used in metal netting
coat with plastic
protective coating for machine part
apply oil and grease
alloying the iron with 18% chromium and 8% nickel that provide a protective oxide coating
alloying the iron
cans of food is covered with a thin layer of tin to provide a protective oxide coating to the cans
tin plating
zinc layer provides a protective oxide coating zinc is oxidized instead of iron
galvanizing
block of magnesium are attached at the intervals of the water piping system & zinc bars are attached to the part of the shup submerged in sea water
sacrificial protection
causes dislocation of iron atoms and creates defects in the crystal structure.
Metalworking
