Urgent Help for IGCSE Chem !

[Trinion]

If the compound decomposes, complete the word equation.
If it does not decompose, write "no reaction"

Potassium Hydroxide --->________________
calcium Hydroxide ----> ______________

Complete the equations for the decomposition of their nitrates:

2KNO₃----> _____+_____
2Ca(NO₃)₃ -----> _____+_______+_______


Thanks in advance!

[Ghost Of Highbury]

calcium hydroxide ----> Calcium oxide + water

Potassium hydroxide --> no reaction

Potassium nitrate --> Potassium nitrite + oxygen

Calcium nitrate --> Calcium oxide + nitrogendioxide + oxygen

[Trinion]

Thank you very much!
Can you explain to me why Potassium Hydroxide has no reaction?

This stuff isn't even in the IGCSE syllabus but it came up last year!

Also, does a metal carbonate decompose to form the metal oxide+ carbon dioxide?

Edit: One more question. Do all group 1 and 2 metal ions form a colourless solution in water?
Is it the same for halogen and transitional metals ion?

[Ghost Of Highbury]

potassium hyrdroxide is stable to heat thus doesnt decompose.  most alkali metal hydroxides do not decompose, except lithium hydroxide.

its dere in the IGCSE syl. check for "thermal decomposition"

and yes, metal carbonate --> metal oxide + CO

[Ghost Of Highbury]

no not all , few metal ions form a white precipitate, green, blue etc. colorless solution is often formed when excess ammonia is added to zinc salt

[Trinion]

Thank you Adi
I still can't find the thermal decomposition in the syllabus!
it certainly isn;t in my textbook? =(

I think you mistook what I meant, I meant say... Sodium chloride dissolves in water, neither ions in aqueous solutions change the colour of the solution correct?

Is it true for other halogens/transitional metal ions when they dissolve in water?

[Ghost Of Highbury]

i'm not sure abt this but i strongly think that it takes the colour of the ppt. colour formed by the cation

fore.g-> CuSO4 -> Cu2+ + SO4(2-)

when added to water, turns blue. blue = Cu(2+)

same with NaCl

so it takes the colour precipitate of the cation

[Trinion]

Cool =)

What about bromine water/solution

Why is it orange or brown? Is it because of the bromine ions?

[Ghost Of Highbury]

bromine water is simply an aqueous solution of Br₂ --> no ions, the colour of Br₂ is brown thus bromine water is brown color.

[Trinion]

Adi, doesn't an aqueous solution of an element simply mean its ions are dissolved in it?

[Ghost Of Highbury]

oh yes, sry, Br- ions are which give the brown color, but if its so , then Br- ions give a cream color, but bromine water is brown ..

[@d!_†oX!©]

see according to what i think....
the bromine ions are brown in colour but,
they form a creamish ppt because of the whole compound lead(II) bromide, and not just Br
so basically i wanna say that the cream colour is due to lead(II) bromide and not just bromide ions

[Ghost Of Highbury]

acutally, my logic says -> lead ->white ppt bromine -> brown ppt --> brown ppt _ white ppt --> cream ppt lol..kidding

but adi, its abt bromine water being brown not lead bromide 

[@d!_†oX!©]

1)i did not get ur logic
2)i replied to what u had asked about bromide ppt being cream

[Ghost Of Highbury]

bleh!