Chemistry: Post your doubts here!

[Cadence]

10.When solid ammonium chloride dissociates at a certain temperature in a 0.500 dm3 container,
ammonia and hydrogen chloride are formed.
NH4Cl (s) NH3(g) + HCl (g)
The initial amount of ammonium chloride was 1.00 mol, and when the system had reached
equilibrium there was 0.300 mol of ammonium chloride.
What is the numerical value of Kc for this reaction under these conditions?
A 0.490 B 1.63 C 1.96 D 3.27
ans is C But how do we get that?

did u get ur ans?

 

[drowning-in-studies]

did u get ur ans?

I keep getting D??

 

[HELLNO]

I keep getting D??

NH4Cl is in a solid state! So whenever you want to find kc you only include gaseous and liquid states (Since its concentration) Its like a rule
The 1 mol of NH4Cl decreased to 0.3 (-0.7)
So each of the products increase from 0 to 0.7 moles
Convert that to concentration
0.7/0.5= 1.4 mol/dm3
Apply the formula of Kc
Kc= 1.4*1.4= 1.96 which is C
Get it?

 

[drowning-in-studies]

NH4Cl is in a solid state! So whenever you want to find kc you only include gaseous and liquid states (Since its concentration) Its like a rule
The 1 mol of NH4Cl decreased to 0.3 (-0.7)
So each of the products increase from 0 to 0.7 moles
Convert that to concentration
0.7/0.5= 1.4 mol/dm3
Apply the formula of Kc
Kc= 1.4*1.4= 1.96 which is C
Get it?

OOHH! Thanks

 

[soumayya]

cananyone helpme with the drawing in 1(b) ?? and 2(d) plzz??

http://onlineexamhelp.com/wp-content/uploads/2016/03/9701_s15_qp_52.pdf

 

[Thought blocker]

ughh!! paper y, y u do no rahem :'(

 

[June Phang]

But how do you decide when to add and subtract? Is it in reference to where the arrows are pointing? What am i missing out?
like, -75+92 or -75-92?

When you change the direction

 

[June Phang]

Q.25 anyone please reply soonn

What is the ans tho

 

[drowning-in-studies]

6 The standard enthalpy change for the reaction
2NF3(g) → 2N(g) + 6F(g) is ΔH
o = +1668 kJ
What is the bond energy of the N–F bond?
A –556 kJ mol–1
B –278 kJ mol–1
C +278 kJ mol–1
D +556 kJ mol–1
Ans is C...How??

 

[Thought blocker]

6 The standard enthalpy change for the reaction
2NF3(g) → 2N(g) + 6F(g) is ΔH
o = +1668 kJ
What is the bond energy of the N–F bond?
A –556 kJ mol–1
B –278 kJ mol–1
C +278 kJ mol–1
D +556 kJ mol–1
Ans is C...How??

delth H / 6
thus 1668/6 = C

 

[drowning-in-studies]

delth H / 6
thus 1668/6 = C

Im really sorry... I just realised I've asked this question before and that you replied
16 days and i forgot
But thank you loads for being so helpful

 

[Thought blocker]

Im really sorry... I just realised I've asked this question before and that you replied
16 days and i forgot
But thank you loads for being so helpful

Lol, happens. Anytime.

 

[drowning-in-studies]

Q 39 and Q 40??

 

[Thought blocker]

Q 39 and Q 40??

39)1 and 2

40) This is easiest last question, i ever saw xD Sorry to say like this, but just u have to manipulate its structure and match with the given compound in question. All three is having that formula after oxidation. Try once, if u dont get ask me. Bored in making that one in 39 xD

 

[drowning-in-studies]

39)1 and 2
View attachment 61409
40) This is easiest last question, i ever saw xD Sorry to say like this, but just u have to manipulate its structure and match with the given compound in question. All three is having that formula after oxidation. Try once, if u dont get ask me. Bored in making that one in 39 xD

39 Okay, got that
40 Yeah okay...but I don't get the 3rd molecule ? ANd hey Q 40 is in the examiner report's particularly difficult

 

[Thought blocker]

39 Okay, got that
40 Yeah okay...but I don't get the 3rd molecule ? ANd hey Q 40 is in the examiner report's particularly difficult

IDK how i found that easiest -_- This was the paper i gave and the only sure answer was this xD
This is your oxidised product of third molecule. CO2 is product as well, i have just shown that main thingy xD

 

[drowning-in-studies]

IDK how i found that easiest -_- This was the paper i gave and the only sure answer was this xD
This is your oxidised product of third molecule. CO2 is product as well, i have just shown that main thingy xD
View attachment 61410

mhmm.. okay then

 

[Thought blocker]

mhmm.. okay then

lol, whats this? got it or not?

 

[Cadence]

hey guys how's the paper today?

 

[drowning-in-studies]

lol, whats this? got it or not?

Yeah I did