[Future Medics]

(Original post by Arusa01)
HAA! Princess?

Princess jajajajaja
Yolo
LOL Scrib

[Arusa01]

(Original post by Future Medics)
Princess jajajajaja
Yolo
LOL Scrib

PM

[Pandamojia]

Hey, how would u know if you need to use silver nitrate or hexane if u want to test halogen/halide?

[Exams v__v]

why does NH3 have a lower boiling point than HF and H2O have a higher boiling point than HF? Help, someone!!

[fiza_1]

(Original post by VRS)
Explain why the thermal stability increases with nitrates and carbonated down group 1 and 2

Also what are the trends we have to know for group 1,2,7 and across the period? Just trends


This was posted from The Student Room's iPhone/iPad App

from group 1 NaC03 downwards ,the carbonates don't decompose when heated
only the nitrates of group 1 from Na downwards decompose
so the thermal stability increases down group 2 meaning the carbonates and nitrates become more stable to heat as the ionic radius of the positive ion increases down the group ie the positive ion becomes larger so polarisation of the carbonated electron cloud

i think the only trends you need to know are :
solubility of group 2 hydroxides and sulfates
thermal stabilities of group 1 and 2
and with group 7 there isnt a trend you need to learn except that the ionization energy decrease and the electro negativity also decreases down the group
the main things you need to know about group 7 are its reactions
and the test for halides

[Pandamojia]

also someone explain steric inheritance!!

[The Doggfather]

(Original post by Pandamojia)
Hey, how would u know if you need to use silver nitrate or hexane if u want to test halogen/halide?

Silver Nitrate for Chloride, Bromide, Iodide ions
Hexane for Chlorine, Bromine, Iodine

[im so fresh]

(Original post by Arusa01)
HAA! Princess?

lol.
meant bride. what your name means in arabic.

[fiza_1]

(Original post by Exams v__v)
why does NH3 have a lower boiling point than HF and H2O have a higher boiling point than HF? Help, someone!!

as HF can form hydrogen bonding so more energy needed and H2O has greater b.p then HF as it can from up to 2 hydrogen bonds with one molecule so much stronger

[Exams v__v]

(Original post by fiza_1)
as HF can form hydrogen bonding so more energy needed and H2O has greater b.p then HF as it can from up to 2 hydrogen bonds with one molecule so much stronger

Even NH3 can form H.B, but still why is it's boiling point lower than that of HF?

[The Doggfather]

(Original post by Exams v__v)
why does NH3 have a lower boiling point than HF and H2O have a higher boiling point than HF? Help, someone!!

H2O has a higher boiling point than HF because it can form 2 hydrogen bonds as there are 2 electron lone pairs on the oxygen while HF forms 1 hydrogen bond. So more energy required to break the intermolecular forces in H2O than in HF.

Not sure about why NH3 has a lower boiling point than HF

[Pandamojia]

(Original post by The Doggfather)
Silver Nitrate for Chloride, Bromide, Iodide ions
Hexane for Chlorine, Bromine, Iodine

Yh but isn't it Chlorine from CH3CH2CH2Cl an atom? Yet...we used silver nitrate?

[VRS]

(Original post by fiza_1)
from group 1 NaC03 downwards ,the carbonates don't decompose when heated
only the nitrates of group 1 from Na downwards decompose
so the thermal stability increases down group 2 meaning the carbonates and nitrates become more stable to heat as the ionic radius of the positive ion increases down the group ie the positive ion becomes larger so polarisation of the carbonated electron cloud

i think the only trends you need to know are :
solubility of group 2 hydroxides and sulfates
thermal stabilities of group 1 and 2
and with group 7 there isnt a trend you need to learn except that the ionization energy decrease and the electro negativity also decreases down the group
the main things you need to know about group 7 are its reactions
and the test for halides

Thank you so much - appreciate it!


This was posted from The Student Room's iPhone/iPad App

[Exams v__v]

(Original post by The Doggfather)
H2O has a higher boiling point than HF because it can form 2 hydrogen bonds as there are 2 electron lone pairs on the oxygen while HF forms 1 hydrogen bond. So more energy required to break the intermolecular forces in H2O than in HF.

Not sure about why NH3 has a lower boiling point than HF

Cant the delta positive 2 hydrogens also form hydrogen bonds? So in all, 4 hydrogen bonds in water molecules?

[fiza_1]

(Original post by Exams v__v)
Even NH3 can form H.B, but still why is it's boiling point lower than that of HF?

as HF has higher electro negativity

[Exams v__v]

Cant the delta positive 2 hydrogens in water molecule also form hydrogen bonds? So in all, 4 hydrogen bonds in water molecules?

[The Doggfather]

(Original post by Pandamojia)
And how would u know to use hexane or silver nitrate to test halide?

Add Silver Nitrate and Dilute Nitric Acid
Chloride - White ppt
Bromide - Cream ppt
Iodide - Yellow ppt

In Hexane
Chlorine - Colourless
Bromine - Orange-Red
Iodine - Pink-Violet

In Water
Chlorine - Colourless
Bromine - Yellow-Orange
Iodine - Brown

If the Halogen is not bonded to another atom, then add to Hexane or Water. Otherwise add Silver Nitrate and Dilute Nitric acid e.g. KCl, KBr

[The Doggfather]

(Original post by Exams v__v)
Cant the delta positive 2 hydrogens in water molecule also form hydrogen bonds? So in all, 4 hydrogen bonds in water molecules?

They can form hydrogen bonds with the oxygen on another water molecule but that's the same as when the oxygen forms hydrogen bonds with hydrogen's if you know what I mean. So don't include them, it's 2 hydrogen bonds per water molecule because of 2 electron lone pairs.

[fiza_1]

(Original post by Exams v__v)
Cant the delta positive 2 hydrogens in water molecule also form hydrogen bonds? So in all, 4 hydrogen bonds in water molecules?

In H2O the O only has 2 pair of lone electrons so only 2 hydrogen bonds can occur.

[Exams v__v]

(Original post by The Doggfather)
They can form hydrogen bonds with the oxygen on another water molecule but that's the same as when the oxygen forms hydrogen bonds with hydrogen's if you know what I mean. So don't include them, it's 2 hydrogen bonds per water molecule because of 2 electron lone pairs.

Thank you so much.