Physics, Chemistry and Biology: Post your doubts here!

[shoaib672002]

shoaib672002 the one i didnt do im stuck on it myself
if i figure it out i will let u knw!

Thanks

 

[ahmed faraz]

common ahmed faraz the physics exams are over

i am in grade 9.
just preparing for IGS

 

[Xylferion]

Thanks

 

[Lola_sweet]

View attachment 43304

THANK YOU SOOOOOO MUCH! now my frustration is gone!!!!!!!!!!!!

 

[Xylferion]

THANK YOU SOOOOOO MUCH! now my frustration is gone!!!!!!!!!!!!

Glad I could help

 

[princess sofia]

here u go , the ones i found missing

 

[Phoenix Blood]

How is electricity produced by an electrical 'cell'? What roles do the electrodes play?

 

[Phoenix Blood]

What's the action of heat on the hydroxides an nitrates of metals?

 

[Xylferion]

How is electricity produced by an electrical 'cell'? What roles do the electrodes play?

The electrode with the more reactive metal, allows electrons to flow to the electrode with the less reactive metal. While this happens, electrical energy is produced due to the flow of the electrons.

 

[Phoenix Blood]

View attachment 43307

The electrode with the more reactive metal, allows electrons to flow to the electrode with the less reactive metal. While this happens, electrical energy is produced due to the flow of the electrons.

How can we decide whether the setup is of a cell or of an electrolysis apparatus?

 

[Masha karroum]

What year is this paper?

its May june 2009 31

 

[Masha karroum]

this is a)

Magnesuim 72% 72g/100g 72/24=3

Nitrogen 28% 28g/100g 28/14=2


Empirical formula

Mg3N2

thank you ALOT!

 

[Xylferion]

What's the action of heat on the hydroxides an nitrates of metals?

In either cases, the action of heat is basically the thermal decomposition of either.

Highly reactive metals such as Na and K are more thermally stable when in the form of carbonates and hydroxides, and thus they will not decompose. However as a nitrate, the two will decompose to form a "Nitrite".

For metals below these, such as Calcium, Zinc and Lithium. The metal hydroxides will decompose to form a metal oxide + water.

For the metals, Zinc, Copper and Lithium, the metal nitrates will decompose to form.

Metal Oxide + Nitrogen Dioxide + Oxygen

For metals lower than Copper, the nitrates will decompose to form:

the Metal + Nitrogen Dioxide + Oxygen.

 

[Xylferion]

How can we decide whether the setup is of a cell or of an electrolysis apparatus?

In an electrochemical cell, chemical energy is converted into electrical energy, as you saw above. The electrical energy is detected by the voltmeter.

In an electrolytic cell, electrical energy from a power source is converted into chemical energy, so that electrolysis can happen.

Just remember this:

Electrochemical cell = Chemical Energy to Electrical Energy

Electrolytic cell = Electrical Energy to Chemical Energy

 

[Phoenix Blood]

In either cases, the action of heat is basically the thermal decomposition of either.

Highly reactive metals such as Na and K are more thermally stable when in the form of carbonates and hydroxides, and thus they will not decompose. However as a nitrate, the two will decompose to form a "Nitrite".

For metals below these, such as Calcium, Zinc and Lithium. The metal hydroxides will decompose to form a metal oxide + water.

For the metals, Zinc, Copper and Lithium, the metal nitrates will decompose to form.

Metal Oxide + Nitrogen Dioxide + Oxygen

For metals lower than Copper, the nitrates will decompose to form:

the Metal + Nitrogen Dioxide + Oxygen.

Is it like this for Na/K :
Sodium nitrate ---> Sodium Nitrite. ?

And For metals lower than Copper, the hydroxides will decompose to form what?

 

[Xylferion]

Is it like this for Na/K :
Sodium nitrate ---> Sodium Nitrite. ?

And For metals lower than Copper, the hydroxides will decompose to form what?

Sodium Nitrite + Oxygen. Forgot to mention that oxygen forms.

Copper Hydroxide will form Copper Oxide.

 

[Phoenix Blood]

Sodium Nitrite + Oxygen. Forgot to mention that oxygen forms.

Copper Hydroxide will form Copper Oxide.

Err... Coppper hydroxide ---> Copper oxide? Where did the H go?

CuOH --- CuO .

The 'H'?

 

[Xylferion]

Err... Coppper hydroxide ---> Copper oxide? Where did the H go?

CuOH --- CuO .

The 'H'?

Cu(OH)2 >> CuO + H2O

There. ._________________________________.

 

[Phoenix Blood]

Cu(OH)2 >> CuO + H2O

There. ._________________________________.

Hehe. Thanks.

 

[Phoenix Blood]

'ElllpP!

Xylferion Awesome12