Chemistry: Post your doubts here!

[Namehere]

Hydrogen bond is between hydrogen and highly electronegative ion ( N , O , F ) .. so B only has this H --- N in ammonia

"Hydrogen bond is between hydrogen and highly electronegative ion ( N , O , F )" Not ion! ^^

 

[sumeru]

Can anyone help please and Expla

in this ?

If you look at the 2nd reaction the double bond in aldehyde is being attacked by CH3CH2O-, which is a nucleophile, and it involves formation of a single product, so it is nucleophilic addition

 

[sitooon]

"Hydrogen bond is between hydrogen and highly electronegative ion ( N , O , F )" Not ion! ^^

See if you can help with this :
was arguing with someone and didnt reach conclusion :
https://www.xtremepapers.com/commun...st-your-doubts-here.9859/page-388#post-749668
Last part

 

[AbbbbY]

they r not in diff directions.... in beta pleated hydrogen bonds form btw diff polypeptide chains and the r diff polypeptide chains
this diagram is lso given in my TB

You're wrong there. They do run in opposite directions. I checked my notes to verify if I was mistaken.

 

[ahmed abdulla]

Paper 5 , http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w12_qp_53.pdf

Question 2b(iii) ( moles )
Question 3 , how to Complete the table > no formulas are given

& Whats is the max. Volume a gas syringe can hold which we are supposed to label here ?

 

[AbbbbY]

please some one help me http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s06_qp_1.pdf

Q23 , Q20 , Q15 , Q17 , Q11 , Q5 , Q6 , Q3 ... answer as much as you can .. so that I don't disturb you and inbox me if required thanks ^_^

3 - D
Na3- so gains 3 electrons.
1s2 2s2 2p6

5 B

Hydrogen bonding exists b/w compounds containing N/O/F.

6 A
Almost picked D overlooking ammonia but it'll be A bec ammonia has Hydrogen Bonding.

11 A?
I'd go with A. OH- produced would react with the H+ ions added to form H2O again which would produce even more HOCl. B will maintain a high conc too, but A will maintain a higher concentration.


15 A
Most definitely A.
AlCl3 exists as a dimer at high temperatures, with the Cl lone pair forming a dative bond with Al.

17 C

Group 7 [O] review.

Cl2 + 2I- -> 2Cl- + I2


20 C?

A and D are out. Always hated these messed up nucleophile electrophile terms. I always mix them up and have to associate them with the word 'pedophile' to realize what they mean.
I guess it's nucleophilic addition because the aldehyde is undergoing a nucleophilic addition reaction. Idk.

23 C in a heartbeat!

A-> Ethanol CH3CH2OH = 46
B-> Ethene CH2=CH2 = 28
C-> Interesting. It can form CH3CH2BR and up to CBr3CBr3. In any case, it'll be this because Br alone > 64.5. I knew this from the many Br79-81 questions I've done so I selected this right away. Done each step to explain.
D-> Chloroethane CH3CH2Cl = 64.5

 

[Haya Ahmed]

3 - D
Na3- so gains 3 electrons.
1s2 2s2 2p6

5 B

Hydrogen bonding exists b/w compounds containing N/O/F.

6 A
Almost picked D overlooking ammonia but it'll be A bec ammonia has Hydrogen Bonding.

11 A?
I'd go with A. OH- produced would react with the H+ ions added to form H2O again which would produce even more HOCl. B will maintain a high conc too, but A will maintain a higher concentration.


15 A
Most definitely A.
AlCl3 exists as a dimer at high temperatures, with the Cl lone pair forming a dative bond with Al.

17 C

Group 7 [O] review.

Cl2 + 2I- -> 2Cl- + I2


20 C?

A and D are out. Always hated these messed up nucleophile electrophile terms. I always mix them up and have to associate them with the word 'pedophile' to realize what they mean.
I guess it's nucleophilic addition because the aldehyde is undergoing a nucleophilic addition reaction. Idk.

23 C in a heartbeat!

A-> Ethanol CH3CH2OH = 46
B-> Ethene CH2=CH2 = 28
C-> Interesting. It can form CH3CH2BR and up to CBr3CBr3. In any case, it'll be this because Br alone > 64.5. I knew this from the many Br79-81 questions I've done so I selected this right away. Done each step to explain.
D-> Chloroethane CH3CH2Cl = 64.5

You're awesome <3 That helped me a lot
Thanks tonnes <3

 

[Haya Ahmed]

Can anyone help me please how did we get this ?!

 

[ahmed abdulla]

Can anyone help me please how did we get this ?!

group II metal nitrate is going to produce metal oxide and nitrogen dioxide gas,the ratio between metal nitrate and metal oxide would be 1:1
5/x+28+96 = (5-3.29)/x+16
equate it u will get the answer

 

[AbbbbY]

Can anyone help me please how did we get this ?!

Oh boy. That's a toughie.

Group II metal nitrate upon heating will produce a metaloxide and NO2 in 1:1

X(NO3)2 -> XO + NO2

Umm. I'd probably tackle it by finding the mols of the metal nitrate and metal oxide in terms of x.

5/(x+(2(14+16*3)=5-3.29/(x+16)
5/x+124 = 1.71/x+16
5x+80 = 1.71x + 212.04
3.29x = 132.04
x = 40.1
so, Calcium.

 

[mahabaloch]

how we get 0.176?

 

[Haya Ahmed]

group II metal nitrate is going to produce metal oxide and nitrogen dioxide gas,the ratio between metal nitrate and metal oxide would be 1:1
5/x+28+96 = (5-3.29)/x+16
equate it u will get the answer

Shokran ^_^

 

[Haya Ahmed]

Oh boy. That's a toughie.

Group II metal nitrate upon heating will produce a metaloxide and NO2 in 1:1

X(NO3)2 -> XO + NO2

Umm. I'd probably tackle it by finding the mols of the metal nitrate and metal oxide in terms of x.

5/(x+(2(14+16*3)=5-3.29/(x+16)
5/x+124 = 1.71/x+16
5x+80 = 1.71x + 212.04
3.29x = 132.04
x = 40.1
so, Calcium.

Thank's Bro

 

[Haya Ahmed]

Btw any idea what is the colour of ( [Ag(NH3)2]+2 Cl-1 ) ?

the reaction of AgCl + NH3

 

[Namehere]

Oh boy. That's a toughie.

Group II metal nitrate upon heating will produce a metaloxide and NO2 in 1:1

X(NO3)2 -> XO + NO2

Umm. I'd probably tackle it by finding the mols of the metal nitrate and metal oxide in terms of x.

5/(x+(2(14+16*3)=5-3.29/(x+16)
5/x+124 = 1.71/x+16
5x+80 = 1.71x + 212.04
3.29x = 132.04
x = 40.1
so, Calcium.

The equation for the Group II nitrate thermal decomposotion is as follows: 2X(NO3)2 ----> 2XO + 4NO2 + O2
5.00g 1.71g (all 3.29g)

You could do it using a bit of algebra or through trial and error. So:
if X = Mg, number of moles of Mg(NO3)2 = 5/148.3 = 0.0337 mol.
Therefore mass os MgO produced = 0.0337 x 40.3 = 1.36g, so can´t be Mg.

if X=Ca, number of moles of Ca(NO3)2 = 5/164.1 = 0.0305 mol.
Therefore mass of CaO produced = 0.0305 x 56.1 = 1.71g

Best way will be fastest way! ^^

 

[Namehere]

Btw any idea what is the colour of ( [Ag(NH3)2]+2 Cl-1 ) ?

the reaction of AgCl + NH3

Well AgCl is a white precipitate. If you add NH3 it usually dissolves.

Do correct me though.

 

[Haya Ahmed]

Well AgCl is a white precipitate. If you add NH3 it usually dissolves.

Do correct me though.

Yeah right .. I totally forgot about the solubility thingy

 

[AbbbbY]

The equation for the Group II nitrate thermal decomposotion is as follows: 2X(NO3)2 ----> 2XO + 4NO2 + O2
5.00g 1.71g (all 3.29g)

You could do it using a bit of algebra or through trial and error. So:
if X = Mg, number of moles of Mg(NO3)2 = 5/148.3 = 0.0337 mol.
Therefore mass os MgO produced = 0.0337 x 40.3 = 1.36g, so can´t be Mg.

if X=Ca, number of moles of Ca(NO3)2 = 5/164.1 = 0.0305 mol.
Therefore mass of CaO produced = 0.0305 x 56.1 = 1.71g

Best way will be fastest way! ^^

My equation is intentionally unbalanced. All I wanted to show was the X(NO3)2 -> XO in a 1:1

And yes. Trial and error + quick calculator work will be quick too.

 

[itallion stallion]

Help needed!
How to draw structure of XeF4( it has 4 bonding pairs and lone pair also)?bond angle also plz?

 

[♣♠ Magnanimous ♣♠]

Help needed!
How to draw structure of XeF4( it has 4 bonding pairs and lone pair also)?bond angle also plz?