Chemistry: Post your doubts here!

[qwertypoiu]

Help.
asadalam
qwertypoiu

hey idk why I didnt get tag alert, have you got your answer yet?

 

[nehaoscar]

Why not C?
Is there a trick or some solution is solving these questions?
Like the electronegativity values are not in the data booklet so any tips on how to calculate these sort of questions to find the largest or smallest overall dipole?

 

[mohhef3]

hey idk why I didnt get tag alert, have you got your answer yet?

View attachment 54801
Why not C?
Is there a trick or some solution is solving these questions?
Like the electronegativity values are not in the data booklet so any tips on how to calculate these sort of questions to find the largest or smallest overall dipole?

qwertypoiu i have both doubts tooo

 

[Xtreamer]

View attachment 54801
Why not C?
Is there a trick or some solution is solving these questions?
Like the electronegativity values are not in the data booklet so any tips on how to calculate these sort of questions to find the largest or smallest overall dipole?

Just remember that Cl , F, N and O are very electronegative and tend to pull electrons toward themselves much.

It cant be C cuz Cl and O dont have much electronegativity difference so its kinda balanced....in B highly electronegative is only O so thats why

 

[nehaoscar]

Help.
asadalam
qwertypoiu

 

[nehaoscar]

qwertypoiu i have both doubts tooo

 

[princess Anu]

why is 2nd statement wrong in both the questions?

 

[asadalam]

View attachment 54801
Why not C?
Is there a trick or some solution is solving these questions?
Like the electronegativity values are not in the data booklet so any tips on how to calculate these sort of questions to find the largest or smallest overall dipole?

Because the Cl cancel out some of the net dipole caused by O.Similar in the case of CCl4 So3 etc where there are E-ve elements but no net dipole

 

[asadalam]

why is 2nd statement wrong in both the questions?View attachment 54811

H+ ions already have 1+ oxidation state so in water it remains same so they arent oxidised.Similar in the next one.Both have 1+ in H20

 

[Abdul Hanan]

 

[princess Anu]

View attachment 54813

C?

 

[princess Anu]

H+ ions already have 1+ oxidation state so in water it remains same so they arent oxidised.Similar in the next one.Both have 1+ in H20

but they have gained oxygen, no? :

 

[asadalam]

but they have gained oxygen, no? :

But there isnt a change in oxidation state.It doesnt matter how many you gain,the Oxidation state is key,

View attachment 54813

A?

 

[princess Anu]

:s why is it D?

 

[mohhef3]

View attachment 54810

how did u get that 3459 kj/mol.ok i got it but u should write LHS not RHS.right?
thx alot mate

 

[princess Anu]

Help please

 

[Tasneem_m98]

Please help ! O/N 2011 p11 question 33

The following statements are all true.
Which of these can be explained, at least in part, by reference to hydrogen bonding?
1 At 0°C ice floats on water.
2 The boiling point of propan-2-ol is 82°C. The boiling point of propanone is 56°C.
3 At 20°C propanal and propanone mix completely.

The answer is B (1 and 2 only are correct).
But i don't understand why cant 3 be correct. Dont propanal and propanone mix due to hydrogen bonding??
Thank you in advance!

 

[asadalam]

Please help ! O/N 2011 p11 question 33

The following statements are all true.
Which of these can be explained, at least in part, by reference to hydrogen bonding?
1 At 0°C ice floats on water.
2 The boiling point of propan-2-ol is 82°C. The boiling point of propanone is 56°C.
3 At 20°C propanal and propanone mix completely.

The answer is B (1 and 2 only are correct).
But i don't understand why cant 3 be correct. Dont propanal and propanone mix due to hydrogen bonding??
Thank you in advance!

No as in propanal the H atom is not bonded to O atom so there will be no H-bonding if you look closely.H bonding requires H to be bonded with a highly electronegative atom like O,but in both cases O is bonded to C not H.

 

[Studydayandnight]

First find the number of moles of K2Cr2O7
n = Vc
13.1*10^-3 *0.100 =1.31*10^-3 moles

As we know the mole ratio of Fe2+ to Cr2O7 2– we can cross multiply and find the number of moles of Fe2+ that have reacted with 1.31*10^-3 moles of Cr2O7 2–, which is equal to 7.86*10^-3 Moles
The Mr of Fe is 55.8g, so then multiply 7.86*10^-3 Moles of Fe2+ with it Mr to get the mass of iron that have reacted with K2Cr2O7 which is equal to 0.439

And then finally find the percentage by mass , 0.439/1*100 = 43.9%

Make sure you round off all the values to an appropriate significant figure when writing and remember to carry the Answers in your calculator for an accurate calculation

Thank you!!

 

[Studydayandnight]

whats the answer

For question 30 right?

How many structural isomers are there of C5H10O12 that are esters?

It's C; 9.