Chemistry: Post your doubts here!

[princess Anu]

In solid ice hydrogen bonding give rise to an open cage like structure in with each water molecule is linked tetrahedrally to four molecules. Thus molecules no longer remain closely packed and mass per unit volume i.e. density decreases. That is why ice floats on water.

why 4?
2 h's and a O will hydrogen bond with other 3 molecules,right?

 

[♣♠ Magnanimous ♣♠]

why 4?
2 h's and a O will hydrogen bond with other 3 molecules,right?

But O has 2 lone pairs right so two hydrogen atoms can form bond to O so 4 h's
I hope you got it

 

[princess Anu]

Q10: how is it D? :0

 

[princess Anu]

 

[♣♠ Magnanimous ♣♠]

Q10: how is it D? :0 View attachment 50972

Of course D should be answer coz PH 6 is acid but weak acid and they undergo dissociation but not fully.
Student P is wrong coz PH 6 is not the value for strong acids ( it should be PH 1-3)
Got?

 

[♣♠ Magnanimous ♣♠]

View attachment 50974

3 is answer coz here are possiblilities --->
1)CH3-CH3
2)CH3-Cl
3)C2H5-C2H5

I hope you got it

I am unsure a bit RoOkaYya G [/USER] help me.

 

[princess Anu]

Of course D should be answer coz PH 6 is acid but weak acid and they undergo dissociation but not fully.
Student P is wrong coz PH 6 is not the value for strong acids ( it should be PH 1-3)
Got?

but why is Q correct

 

[♣♠ Magnanimous ♣♠]

but why is Q correct

Coz PH 6 are weak acids and they dont undergo complete dissociation whereas strong acids fully dissociates when dissolved in water.

 

[princess Anu]

3 is answer coz here are possiblilities --->
1)CH3-CH3
2)CH3-Cl
3)C2H5-C2H5

I hope you got it

I am unsure a bit RoOkaYya G [/USER] help me.

But i think these should be the forms :/

 

[♣♠ Magnanimous ♣♠]

But i think these should be the forms :/

Oh shit! I messed up
You are correct

 

[asadalam]

but why is Q correct

Neutral Ph is 7,q said the extent of dissociation in Y is higher as it changes the value of water by 2 whereas acid changes by -1 unit,hence q is right.

 

[Al. Ahmad]

june 2011 paper 41 question 8 (b) part..
it is related to two way chromatography..
can anyone pleaaaase help?

 

[immie.rose]

june 2011 paper 41 question 8 (b) part..
it is related to two way chromatography..
can anyone pleaaaase help?

take it this way: Solvent 1 is responsible for separating the 'dots' height-wise. And Solvent 2, length-wise.
for b(i) you can see the 'dot' marked with red circle is the answer. this 'dot' couldn't go up height-wise, because it is insoluble in solvent 1. but it moved towards right due to its solubility in solvent 2.
for b(ii) you would notice two dots are at the same height. This suggests that although they gained height due to their solubility in solvent 1, they got separated only due to solvent 2, as one of the 'dots' moved further to the right than the other.
Hence, these two dots should be marked as A and B.
Hope that helps.

 

[Muskan Achhpilia]

Hey please can someone help me out with all these questions?I have also added the marking scheme.


Thanks a lot!

 

[irtixahaider]

can somebody please upload all the end of chapter answers to the coursebook by roger norris?

 

[princess Anu]

 

[princess Anu]

Can someone please solve these..
They are from Electrochemistry & Kinetics

 

[princess Anu]

pleaseeee

 

[The Chill Master]

View attachment 51093 pleaseeee

As far as i think they are asking for temperature change means your solution was at 6 degrees Celsius and it had 50cm^3 solution you added another 50 what will be your temperature change.Thermometer reading will be 6 degrees Celsius but since they are asking for temperature change 12-6.

 

[Metanoia]

View attachment 51093 pleaseeee

Temperature increase (due to heat of neutralization) should still be 6 degree celsius.

Expt 1: 50cm3 of acid + 50 cm3 of alkali (0.05 mol of water formed, releasing heat)
Expt 2: 100cm3 of acid + 100 cm3 of alkali (0.1 mol of water formed, releasing heat)

Basically you are generating 2 twice the amount of heat in expt 2, but its used to heat up twice the volume of solution. So temperature rise is the same in both experiments.

More importantly in this question, mixing any equal volumes of acid and alkali would give you a 6 degree celsius rise.