Chemistry Unit 3B Help

[jtbteddy]

I was revising for my Paper 3b using past papers, and i have a problem:
In the May 2010 question paper of Edexcel, Unit 3b, I don't understand question 1 at all.
In the user guide it says that on heating a carbonate, carbon dioxide is released for carbonates of metals except Group 1, so why is carbon dioxide released on heating this sample if the anion is Lithium and Lithium is in Group 1?
And for question 1c, what is the white solid formed? And why does it form? I need this question fully explained to me.

 

[DC1313]

Lithium carbonate is the only Group 1 metal that decomposes on heating to give calcium oxide and carbon dioxide. Similarly it is the only Group 1 nitrate that decomposes on heating to give nitrogen dioxide, oxygen, and the oxide; other Group 1 nitrates give oxygen and the nitrite. So in a nutshell lithium carbonate and nitrate act like Group 2 carbonates and nitrates on heating.

In 1 c the white solid is lithium oxide because like I said lithium carbonate gives you lithium oxide and CO2 gas. This dissolves in water to give lithium hydroxide and hydrogen Hope it helped.

 

[jtbteddy]

But the edexcel user guide states that "group 1 nitrates (other than Li) evolve oxygen" so how can lithium nitrate evolve oxygen?

 

[IGCSE Abdullah]

Please let me know whats the difference between pi and sigma bounds and how to draw them?? PLEASE URGENTLY NEEDED!!

 

[jtbteddy]

A double bond is made up of a pie bond and a sigma bond, whereas a single bond is made up of solely a sigma bond

 

[DC1313]

But the edexcel user guide states that "group 1 nitrates (other than Li) evolve oxygen" so how can lithium nitrate evolve oxygen?

Maybe it meant that Group 1 nitrates other than lithium nitrate evolve oxygen ONLY, but lithium nitrate gives out oxygen as well as nitrogen dioxide.

 

[jtbteddy]

Ohhhh okay that makes sense, thank you soooo much!!!
And how am I supposed to know that lithium oxide is the white solid? It isn't mentioned anywhere in the user guide

 

[DC1313]

Ohhhh okay that makes sense, thank you soooo much!!!
And how am I supposed to know that lithium oxide is the white solid? It isn't mentioned anywhere in the user guide

your welcome ! and well just remember that all group 1 and group 2 oxides and hydroxides are white solids

 

[jtbteddy]

Okay, great, thanks!