Electrolyisis - How Hard Can It Be

8/18/2019 Electrolyisis - How Hard Can It Be

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Yehya Awad 10c “Electrolysis” How hard can it be? Chemistry Project

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“Electrolysis” How hard canit be?

“A simple guide for idiots.” -Yehya Awad (Author)

“Perfect for idiots who knownothing about science.”

-www.re iew.com

“At !rst " was like #" don$tunderstand% &hy can$t "understand%.$. 'ut this guidechanged e erything% "diots likeme can !nally ha e a chanceto get a .” - nknown


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Electrolysis:

First of all what is electrolysis ? Electrolysis is where yo! "asselectricity thro!#h an electrolyte in this case salt water$ %hen thisis done the water a""ears to be boilin# e&en tho!#h it's not &eryhot$ %ell what's ha""enin# is m!ch cooler and a lot di(erent thanboilin# water$ )et me e*"lain$$$

+his reaction is act!ally a decom"osition reaction $ Howe&er theres!lt de"ends on the ty"e of material yo! !se for the electrodes $

For instance !sin# "a"er cli"s which are mostly iron and co""eryo! #et hydro#en #as and a com"o!nd of iron ,nown as ironhydro*ide$ Yo! #et this res!lt beca!se of the "rocess ofdecom"osition$ %hat act!ally ha""ens is that the electricity brea,sthe water into hydride and hydro*ide ions $ A hydride ion is"ractically a hydro#en atom witho!t its electrons$ Hydro#en doesnot want to stay an ion for lon# when it's free so it joins !" withanother hydro#en atom to form hydro#en #as$ +he hydro*ide ioncombines with the iron -or co""er. in yo!r "a"er cli"s to form ironhydro*ide$ +hat's the #reen st!( that yo! see in yo!r lid$

If you were to do this with carbon electrodes (such as the graphite in a pencil: graphiteis dense carbon.), you get hydrogen gas and chlorine gas. You get the chlorine out ofthe salt water (because salt water is actually a solution of sodium and chlorine ions inwater). The reaction produces hydroxide as well, but it displaces the chlorine in thesolution. You can tell this is happening because the water becomes basic becausesodium and hydroxide ions in water is a strong base . The chlorine, because it's an ion,doesn't want to stay that way for long when it's alone, so it forms chlorine gas (Youwould recogni e the smell of chlorine). The reason you get this result is becausecarbon, in its graphite form, is not reacti!e , li"e metals are. #ow you "now$

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e nitions2

• Electrolyte: A s!bstance that cond!cts anelectric c!rrent when molten or dissol&ed inwater with chemical reactions at theelectrodes$

• Non-Electrolyte: A s!bstance that doesnot cond!ct in the li3!id "hase$

• Weak Electrolyte: A "oor cond!ctor ofelectricity beca!se it is only "artially ioni4ed5 there are mainly molec!les few ions$

• Strong Electrolyte: A #ood cond!ctor ofelectricity beca!se it is com"letely ioni4ed$

• Electrolysis: +he "rocess of "assin# anelectric c!rrent thro!#h a s!bstance andbrin#in# abo!t a chemical reaction$

• Electrodes: Pieces of metal or carbonthro!#h which the c!rrent enters and lea&esthe electrolyte$

• Cathode: +he ne#ati&e electrode$

• Anode: +he "ositi&e electrode$

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+he Princi"le of Electrolysis2

1$ Electrons 7ow from the battery tothe cathode$

/$ Positi&e ions -metallic orhydro#en. in theli3!id are

attracted to this ne#ati&eelectrode$

6$ +he "ositi&e ions acce"telectrons from thecathode and metals orhydro#en are formed atthe cathode$

8$ Electrons 7ow from theanode to the battery or "ower s!""ly$

9$ :e#ati&e ;ons -non


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E*am"les of Electrolysis2

1 st e*am"le2

>olten odi!m Chloride with inert electrodes;ons "resent2 :a @ Cl<

Cathode2

:a @ @ e < :a <

/ nd e*am"le2

Anode2

/Cl < < /e < Cl /

A3!eo!s co""er -;;. s!l"hate with carbon electrodes$;ons "resent2 C! /@ -a3. 8 /


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Past paper questions:

Question 1

escribe what yo! wo!ld see when a3!eo!s co""er -;;.s!l"hate is electroly4ed !sin# carbon electrodes$ B8 mar,s

Model ans er:A colo!rless #as-1 mar,. o*y#en is formed at the anode$ A

brown de"osit of co""er-1mar,. at the cathode$ +he sol!tionchan#es from bl!e-1 mar,. to colo!rless-1 mar,.$

!ips: +a,e care to answer the 3!estion$ Here yo! m!st state what

wo!ld be seen" Yo! are ad&ised to say what occ!rs at eachelectrode$ Colo!rless is essential here clear wo!ld be wron# 5 yo!can ha&e a clear bl!e sol!tion$

Question #

>a#nesi!m is man!fact!red by the electrolysis of its $oltenchloride$ E*"lain why it cannot be obtained by the electrolysis ofits a3!eo!s chloride by #i&in# the reactions at the electrodes in

both cases$ B= mar,s

Model ans er:;n an a3!eo!s sol!tion of ma#nesi!m chloride >#/@ and

H@-1 mar,. mo&e to the cathode$ Hydro#en is formed-1 mar,.$

At the cathode /H@ @ /e< H/ -1 mar,. D+he hydro#enions are from the water$ +he only "ositi&e ions in moltenma#nesi!m chloride are >#/@-1 mar,.$

At the cathode >#/@ @ /e< ># -1 mar,.At the anode -in both cases. /C)< < /e< Cl/$

=


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E*tra sSusan as in che$istry" Susan is no $ore% &or hat shethought as ' #( as ' #S( ) "

A university professor set an examination question in which he asked what the differencebetween ignorance and apathy is. The professor had to give an A+ to a student whoanswered: ! don"t know and ! don"t care.#$ %ichard &ratt' &acific (omputer )eekly' * ,uly -

At the end o& the se$ester% a 1*th-grade che$istry teacherasked her students hat as the $ost i$portant thing thatthey learned in la+" A student pro$ptly raised his hand andsaid% ,Ne er lick the spoon",

An electron sitting in a prison asked a second electroncell$ate% ,What are you in &or., !o hich the latter replied%,/or atte$pting a &or+idden transition",

ome 3!estions2

G2 %hy do chemists call heli!m c!ri!m and bari!m the medicalelements?A2 eca!se if yo! can't heli!m or c!ri!m yo! bari!mI

G2 ;f H


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Electrolyisis - How Hard Can It Be