Factors influencing rate of corrosion (1 Viewer)

[inasero]

Would someone care to share their experimental results with me?
At school, the procedure used was really dodgy so we werre relegated to making qualitative observations stead of quantitative....
Also what I can't explain is that the rate of corrosion for 2 copper electrodes dipped in 0.5M sol'n of CuSO4 was greater than that for copper dipped in 1M solution...and I don't think this can be simply attributed to our chemicals used since other classes did the same thing and they found that this was the case as well...
On last point- why does yellow shit flake off the copper anode in copious quantities?

 

[+:: $i[Q]u3 ::+]

increased corrosion w/

increased temp (fridge vs room temp)
increased oxygen concentration in water (aerated vs boiled/oiled)

when placed in acid, the metal did not corrode, but instead reacted with the acid (HCl and ethanoic)

was CuSo4 ur salt one? Our salt one was screwed too...We used NaCl and our teacher said increased concentrations should have increased rate of corrosion... but our NaCl ones didn't corrode at all... (???) she said we might have dirty test tubes...

hmm... dunno if this helps...

 

[+:: $i[Q]u3 ::+]

oh right did u want quantitative results??
hehe oops sorry.... we didn't bother either.

 

[inasero]

haha nar dont worry bout it...hey i think we are talking about different practicals here, since you tested the effect of temperature and oxygen concentration, what we did was an electrolysis (sorry for confusing you b4) experiment which involved placing two copper electrodes in CuS04 sol'n, electrolysing and supposedly observing before and after weights in order to determine the rate of electrolysis (yeah got it now! NOT corrosion sorry...) we were supposed to test the effect of different currents on the rate of deposition (change the voltage on the transformer), the effect of electrode size (use different size copper strips), the effect of electrode separation (use differeing amounts of wooden blocks to keep them apart) and the effect of electrolyte concentration (the only one we did, and afterwrds nothing else since we got discouraged)
but since our results were dodgy, as I mentioned, we had to make visual inspections...now that were on the same wavelength, could you clarify these issues for me?
Oh and send my regards to Jun Lee

 

[+:: $i[Q]u3 ::+]

haha sure...
do u go to saesoon?

 

[inasero]

yes...i do 0_o"

 

[Hottieflossy]

everyone has to have done basically the same experiments cuz they r in the syllabus.

increse temp...increased rate of corrosion
low pH...increased rate of corrosion
high oxygen concentration...increased rate of corrosion...but with this last one, in the ocean, for example, the concentration of oxygen actually decreases(respiration) as you go further down so any object under water(kilometres down) would not be so rusted.
you wopuld have studies this when speaking about the titanic..blah blah blah

 

[Hottieflossy]

yeh and salt also increases the rate of corrosion because it provides the ions for the elctrolyte or something along those words..who knows

 

[Dangar]

I'm doing an experiment like this, and i have boiled some distilled water, and put it in a stoppered test tube for a control so i can say for sure that the rust is actually coming from the nail thats corroding. i got that from a book, but why did i have to boil the water? Anyone know?

 

[hipsta_jess]

coz boiling the water helps get rid of any impurities and other stuff that could enhance the corrosion..oh and the .5 M being greater than the 1 M, its coz of [electrolyte]

edit: whoops, apparently i am wrong. well sorta wrong, i still reckon im kinda right...coz O2 is classed as 'other stuff that will enhance the corrosion'..oh well.

 

[Piper_Aviator]

Originally posted by Dangar
I'm doing an experiment like this, and i have boiled some distilled water, and put it in a stoppered test tube for a control so i can say for sure that the rust is actually coming from the nail thats corroding. i got that from a book, but why did i have to boil the water? Anyone know?

No no hipsta_jess, boiling the water is to get rid of any dissolved oxygen present in the water. Dissolved oxygen can affect the rate of corrosion. You place a stopper on the top to prevent any oxygen from dissolving back into the water. BUT there is still oxygen left in the test tube for it to dissolve back into solution. So u can pour a layer of oil on top of the water. This prevents any oxygen from dissolving back into the water. Hope that helps Dangar.

 

[inasero]

good work piper