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Biology; Chemistry; Physics: Post your doubts here!

black widow

black widow

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Ayyan :D said:
All ions migrate.
Cations migrate to the cathode.
Anions migrate to Anode.

It's the deposition which counts.
Don't mix MIGRATING And DEPOSITION.
OH- and Cl- both migrate to ANODE.
But CHLORIDE ION gets deposited if the solution is concentrated.


And yes, the anions should be concentrated.
The ANION is always concentrated in Concentrated solutions.
If they mention ''Dilute''.. then you have to deposit the OH- Ion.
But if they say CONCENTRATED or they don't mention anything, than you have to assume it's concentrated.
Click to expand...


only metals can deposit as the ions can turn back to metal at the cathode. Non-metals are NOT deposited
for example in electrolysing conc aqueous CuCl2 using inert electrodes, the reaction for the cathode will be
Cu+2 (aq) + 2e- ------> 2Cu (s)

for the anode it will be
2Cl- (aq) ----------> Cl2 (g) + 2e-

Cl2 is discharged as it is in a higher conc and because the Cl- ions give up electrons more readily than OH- ions do IN THIS CONC SOLUTION.
Cl2 is a gas at room temp and pressure
deposition refers to only metals as they are solids at room temp and pressure (except mercury. mercury is a liquid at room temp and pressure)
at the anode Cl- ions form molecules and become Cl2 gas

(notes. in conc solutions only the halogens will be discharged at the anode instead of OH-)
the halogens are the group 7 elements
SO4- cannot be discharged
 
snowbrood

snowbrood

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Nabeel.Ahmad

Nabeel.Ahmad

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Ruman Wajih said:
What is meant by Thinking Distance and Breaking Distance. (Kinematics)
Click to expand...


Thinking distance is the distance traveled by the vehicle when the driver is thinking about braking.
Breaking distance is the distance traveled by the vehicle when the brakes are being applied, till it comes to rest.
 
Nabeel.Ahmad

Nabeel.Ahmad

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Qasim Hafeez said:
Many other element also react together how find their formula?
Click to expand...


Many reacts take place on earth.
They are not always between ''Elements''.
Compounds react with Elements. Compounds react with other compounds.
In order to find the formula of an ionic compound formed between two elements.
You just swap their valencies.
Like Na+1 and Cl-1
Forms NaCl.

Mg+2 and O-2
Swapping them, we get Mg2O2.. which can be simplified and written as MgO. (Magnesium oxide, which has a melting point of 2800 and is used as refractory material for blast furnaces)

This is only for ionic compounds.
For covalent, you have to learn the formula.
H2O is the universal formula of water.
CO2 is the universal formula of Carbon Dioxide.
CO is for Carbon Monoxide. You need to learn these, look at their structures, their bonding and understand it and that's the formula.
 
Q

Qasim Hafeez

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Nabeel.Ahmad said:
Many reacts take place on earth.
They are not always between ''Elements''.
Compounds react with Elements. Compounds react with other compounds.
In order to find the formula of an ionic compound formed between two elements.
You just swap their valencies.
Like Na+1 and Cl-1
Forms NaCl.

Mg+2 and O-2
Swapping them, we get Mg2O2.. which can be simplified and written as MgO. (Magnesium oxide, which has a melting point of 2800 and is used as refractory material for blast furnaces)

This is only for ionic compounds.
For covalent, you have to learn the formula.
H2O is the universal formula of water.
CO2 is the universal formula of Carbon Dioxide.
CO is for Carbon Monoxide. You need to learn these, look at their structures, their bonding and understand it and that's the formula.
Click to expand...


In some formula in book, there is 2K reacting with some elements?
Why there is a 2 in it? Potassium symbol is only K.
 
Nabeel.Ahmad

Nabeel.Ahmad

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Qasim Hafeez said:
In some formula in book, there is 2K reacting with some elements?
Why there is a 2 in it? Potassium symbol is only K.
Click to expand...


2 moles of Potassium are reacting.
But it should be read as Potassium.
It's just that after balancing these numbers are adding to the formulas.
 
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