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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: s3a on May 04, 2009, 11:14:25 PM

Title: Electrochemistry (Grade 11) Minor lack of understanding of my notes
Post by: s3a on May 04, 2009, 11:14:25 PM

Can someone explain what exactly is being said below the orange line please?

Like the text near "ex:" doesn't even relate chronologically at least to what is being portrayed beneath. Am I wrong? Is it being portrayed chronologically? Like can someone break down what the notes are saying for me so that I could understand it better?

Any help would be greatly appreciated!
Thanks in advance!

Title: Re: Electrochemistry (Grade 11) Minor lack of understanding of my notes
Post by: UG on May 05, 2009, 01:57:51 AM

Okay, so here we have:

Mg + Zn²⁺  :rarrow: Mg²⁺ + Zn

From this we know: Mg is more easily oxidised than Zn
Then:

Sr + Mg²⁺  :rarrow: Sr²⁺ + Mg

From this we know: Sr is more easily oxidised than Mg.
So far we have from easiest to hardest we have: Sr - Mg - Zn

Then:

2Al + 3Zn²⁺  :rarrow: 2Al³⁺ + Zn

We know: Al is more easily oxidised than Zn, so it must be below zinc.

Lastly:

3Mg + 2Al³⁺  :rarrow: 3Mg²⁺ + 2Al

From this we get: Mg is more easily oxidised than Al, so it must be below Al.

Therefore the final order goes: Sr - Mg - Al - Zn  :)
Understand it now? :)

Title: Re: Electrochemistry (Grade 11) Minor lack of understanding of my notes
Post by: s3a on May 07, 2009, 02:05:04 PM

Thanks! I get it now :D

like I get the Toughest to Easiest with the chemical systems part.

However, I do not understand the part that says: "Mg reacts with Zn2+ but not Sr2+. Al reacts with Zn2+ but not Mg2+. Average the 4 metal from least to most easily oxidized."

Title: Re: Electrochemistry (Grade 11) Minor lack of understanding of my notes
Post by: UG on May 07, 2009, 07:17:30 PM

Quote from: s3a on May 07, 2009, 02:05:04 PM

However, I do not understand the part that says: "Mg reacts with Zn2+ but not Sr2+. Al reacts with Zn2+ but not Mg2+.

Mg will reduce Zn²⁺ but not Sr²⁺.
Al will reduce Zn²⁺ but not Mg²⁺.

Title: Re: Electrochemistry (Grade 11) Minor lack of understanding of my notes
Post by: s3a on May 09, 2009, 04:27:20 PM

Are you sure you meant reduced and not oxidized? because as written on the image: "Certain metals can be OXIDIZED more easily than others. It is related to how "hungry" the substance is for electrons."

(What I asked you to confirm was the example of the above quotation)

Title: Re: Electrochemistry (Grade 11) Minor lack of understanding of my notes
Post by: Astrokel on May 09, 2009, 06:16:34 PM

UG is right as Mg and Al are the reducing agents. Your quotation is correct but the second part can be misleading.

http://en.wikipedia.org/wiki/Reactivity_series