two confusing dot points (1 Viewer)

[Sirius Black]

describe factors that affect an electrolysis reaction
-effect of concentration
-nature of electrolyte
-nature of electrodes

This looks quite similar to the prac"plan and perform a first-hand investigation and gather first-hand data to identify the factors that affect the rate of an electrolyte reaction"
Q1:Could any1 tell whether the nature of electrolyte + electrodes have any effect on the RATE of electrolysis plz?

Q2:for the second dot point above, is there any other factor affecting the rate of electrolysis apart from the temperature, conc of electrolyte and distance between eletrodes?

 

[tennille]

Increasing the concentration of the electrolyte will increase the rate of electrolysis.

The greater the area of the electrode immersed in the electrolyte, the greater the rate of electrolysis.

The further apart the electrodes are, the lower the rate of electrolysis.

The greater the voltage applied, the greater the rate of electrolysis.

And yes, the nature of the electrodes and electrolyte do affect the rate of electrolysis. Inert electrodes such as graphite or platinum dont react, but copper can. So this can lead to more than one reaction occurring.

The second dot-point is simply the practical to prove the first dot-point.

As for your second question, all of the above factors and acidity can affect the rate of electrolysis. Acidity encourages more corrosion than basicity, but according to this practical, salt water results in a higher corrosion rate than acidic solutions.

 

[Sirius Black]

As for your second question, all of the above factors and acidity can affect the rate of electrolysis. Acidity encourages more corrosion than basicity, but according to this practical, salt water results in a higher corrosion rate than acidic solutions.

Isn't this prac all about electrolysis rather than CORROSION?

also got another question- why is salt water results in higher rate of corrosion than acidic solution?
(I know in low pH like <3, no corrosion occurs cuz the metal directly reacts with the acid but what about at pH>3?)

 

[dr3amy]

salt water doesnt necessarily cause faster corrosion than acidic they're quite similar and sometimes acidic is more than salt, but salt water causes rusting because its a better electrolyte providing a conducting path between the the anodic and cathodic site & so speeds up the corrosion process

 

[Haku]

...baka.

of course salt water cause more corrosion. it act as an electrolyte. where it can carry two and ways the water and oxygen the the metal and at the same time carry away the oxides that form causeing further corrosion underneath

while acid is stronger. higher oxidation potential than just water and oxygen.

 

[tristambrown]

Re " salt water causes rusting because its a better electrolyte " [than acids]

Do you have a reference for this as i would be interested to know which is the better electrolyte - acids or ionic compounds.

I ask because i know acids can be excellent electrolytes and have found acids to actually out perform salts in home electrolysis experiments.

Before stating that salts "are better electrolytes" i would really want to make sure that it was a: correct and b: easily referencable to enable the examiner to check this.

Salt water results in higher rate of corrosion when Al is involved as the Cl^- ions react with the Al2O3 layer effectively disabling Aluminium's passivating layer - hence pitting on Al "tinnies" boats & Al near the ocean (window frames etc)

Re any other case of salt water being more effective than acids at increasing rate of corrosion - I dont know that this is necessarily true. If someone has references that conclusively prove this one way or the other i would love to see them but until i know for sure i will not be mentioning it in an exam

- remember correct relevant chem gets the mark, irrelevant chem gets ignored, incorrect relevant chem can DEDUCT a mark (according to my chem teacher anyhow)