help in chemistry... an electrolysis question

[waleedsmz]

http://www.xtremepapers.net/CIE/Cambrid ... 1_qp_3.pdf

question 4/f

Why is the answer hydroxide while knowing that iron oxide alone is a basic oxide which could increase the pH?
the first thing I thought about is oxide ion...

 

[XPFMember]

rust is iron(III)oxide,right! so increase in pH means sunstance getting alkakline which is due to hydroxide io,coz in general we know pH is caused due to conc. of oxides and hydroxides in sol. for alkalis and hydrogen ions for acids!!

 

[SuperXDE]

http://www.xtremepapers.net/CIE/Cambridge%20IGCSE/0620%20-%20Chemistry/0620_w01_qp_3.pdf

question 4/f

Why is the answer hydroxide while knowing that iron oxide alone is a basic oxide which could increase the pH?
the first thing I thought about is oxide ion...

pH measure increases with the excess of Hydroxide ions , and imbalance between both Hydroxide and Hydrogen ions.

 

[waleedsmz]

ok I got both of your answers... But does hydroxide ions just stand there alone ??? I mean without a positive ion??? or do they react with iron?

 

[XPFMember]

actually this hydroxide ion is present in the ionic compund (hydrated) iron(III)hydroxide[rust]

 

[waleedsmz]

I think rust is iorn(III) oxide ^o)

 

[XPFMember]

i am sorry u r right it is iron(III)oxide, anyhow it is a metal oxide and thus is basic!!JazkAllah for pointing my mistake!!

 

[waleedsmz]

you're welcome jazk allah