Chemistry: Post your doubts here!

[Mathemagical]

ph is 7, that is neutral.

I'm not too sure about this myself, but there are 2 products which are hydroxides and if the pH were 14 there would be a greater concentration of OH- ions in the solution and the hydroxides would form more readily.

 

[Mathemagical]

But then how do you know that definitely 0.25 of propene and 0.25 of methane are formed?
Like it could be 0.1 and 0.4 or anything right?

This question involves trial and error and balancing equations. It could be 1:4, but then the molecule would have a lot of carbon atoms and is not included in the options available.

 

[ciephobia]

how do i get the answer

 

[nehaoscar]

Why B? Why not C?

 

[ciephobia]

View attachment 54431
Why B? Why not C?

diagnol relationship; beryllium is diagnol to aluminium in the periodic table.

 

[nehaoscar]

diagnol relationship; beryllium is diagnol to aluminium in the periodic table.

Whoa i wasn't taught this! Does this apply to all elements?

 

[nehaoscar]

 

[ciephobia]

Whoa i wasn't taught this! Does this apply to all elements?

don't worry, it is not a big chapter but covers some concepts.
just read about it here: http://www.chemguide.co.uk/atoms/bonding/electroneg.html on the bottom of the page.

 

[nehaoscar]

I know it's +2 with cold but how is it -1 with hot?

 

[nehaoscar]

Why is 2 incorrect?

 

[ciephobia]

View attachment 54432

is it D?

 

[nehaoscar]

How is 1 correct?
N goes from +3 to 0 only ... no other change so show redox??

 

[nehaoscar]

is it D?

Yes
How?

 

[nehaoscar]

How is 1 correct
and 2 and 3 wrong?

 

[ciephobia]

Yes
How?

because

• 2NaBr(s) + 2H2SO4(l) ==> NaHSO4(s) + Br2(g) + SO2(g) + 2H2O(l)
  acid is a proton (hydrogen) donor and NaBr went to NaHSO4, gaining a hydrogen.
• oxidation also occured as The oxidation state of bromine changes from –1 in Br–, to 0 in Br2 (oxidation, increase in oxidation state)

 

[qwertypoiu]

Could you please explain a bit more?
I mean like the others are not polar either right?

Ethanol and water are polar .
The option D has to do with freezing not melting.

 

[qwertypoiu]

View attachment 54436
How is 1 correct
and 2 and 3 wrong?

Ca is 2+. The CH3CO2- ion is -1.
So two organic ions are required per Ca2+ ion.

 

[phanttasy]

1 mol of (NH4)2CO3 has 2 moles of nitrogen atoms so O.65 moles will have 1.3 moles of nitrogen ATOMS
and O.65* (14*2+ 8+12+16*3) = 62.4 g of this compound give us 1.3 moles of nitrogen atoms...

This is what I think.. Lets c what others say

Oh.. I see... Is it also means that 1 mole of (NH4)2CO3 has 3 mole of oxygen atoms/ 1 mole of carbon/ 8 mole of carbon atoms?

 

[qwertypoiu]

View attachment 54434
Why is 2 incorrect?

Effective collision refers to collisions with sufficient energy to react. Since temperature did not change, there is no change to proportion of such collisions.

 

[qwertypoiu]

View attachment 54435
How is 1 correct?
N goes from +3 to 0 only ... no other change so show redox??

Cl went from -1 to +1 (in OCl- ion)