Chemistry: Post your doubts here!

[A*****]

Ester was D

No it was B....a cyclic compound was formed with two ester bonds....it was C3 something ig

 

[haseeb62]

Answer to the last question?

 

[Hisham Khan]

Answer to the last question?

B

 

[Sheraz ali]

B's dipole is 6 multiplied by the dipole of C-H, whereas C's dipole is 2 multiplied by the dipole of C-Cl.

Why???

 

[I Only ask questions]

I cannot get through number (c) though I got number (b)
Please help

 

[Sheraz ali]

View attachment 64233 View attachment 64234

I cannot get through number (c) though I got number (b)
Please help[/QUOTE

 

[I Only ask questions]

How did it come

 

[IN NEED OF HELP]

Guys I did GCSE A-Levels by Cambridge International Examinations and I got 2 C's and 2 D's. However I have good SAT score. I secured 1360 in SAT 1 which includes Mathematics and English. I also did IELTS and secured 6.5 out of 9.0. Is this score good enough to get admitted in USA and getting scholarship?

 

[Unknown202]

Which process does not involve either oxidation or reduction?
A formation of ammonium sulphate from ammonia and sulphuric acid
B formation of nitrogen monoxide from ammonia
C formation of sulphuric acid from sulphur
D formation of zinc from zinc blende (ZnS)
someone help why is it A?

 

[A*****]

Which process does not involve either oxidation or reduction?
A formation of ammonium sulphate from ammonia and sulphuric acid
B formation of nitrogen monoxide from ammonia
C formation of sulphuric acid from sulphur
D formation of zinc from zinc blende (ZnS)
someone help why is it A?

Write down the equation for each one and see in which equation the oxidation state of all the elements is unchanged...that will be the one with no redox reaction

 

[Unknown202]

can someone solve tht?

 

[A*****]

View attachment 64262
can someone solve tht?

Is it "...begin to boil or something?" And is the answer D?

 

[Hamnah Zahoor]

I need some help on this mcq. The answer is 1 and 2


View attachment 64265

Q37 For a molecule to be in same plane it should have an angle of 120 degree in its compound
option A contains a 120 degree angle due to C=C bond.
I think option B have planar structure for it can also exist as cyclopropane which have angle of 120 degree.
From the examination report:
Question 37 The most commonly chosen incorrect answer was C. This suggests that most candidates knew that the three carbon atoms in propane all lie in the same plane. The six carbon atoms in 2,3-dimethylbut-2-ene also all lie in the same plane, since the bond angles at an sp2 hybridised carbon atom are very close to 120°, and the π bond prevents rotation. However, the six carbon atoms in cyclohexane do not lie in the same plane, they are all sp3 hybridised with bond angles close to 109°.

 

[Bishnu Dev]

What is the concept behind a (ii) and a (iii) ???

 

[Hamnah Zahoor]

What is the concept behind a (ii) and a (iii) ???

(ii) As, Ksp = [Ca2+][SO4 2-]
(3*10^-5)= (x)(x)
(3*10^-5)=x^2
x=5.48*10^-3

CaSO4 -----> Ca2+ + SO42-
1 mol of CaSO4 : 1 mol of Ca2+
thus, conc. will be same
[CaSO4] = 5.48*10^-3

(iii) conc.of CaSO4 : conc. of H2SO4 (acid rain)
1 : 1
conc. of H2SO4 (acid rain)= 5.48*10^-3
moles = (5.48*10^-3)*100
0.548 moles
As stated in the question statement that the carbonate is converted into soluble sulphate thus we are supposed to calculate the mass of soluble sulfate that is the mass lost. 1 mol of H2SO4 : 1 mol of CaSO4
0.548*( 40.1+32+(16*4)
74.58 g -------------> that is the mass lost.

 

[Asim Shah]

Does any body have Philip Alan Magazines Chemistry review

 

[Bishnu Dev]

do we have to study about the chemical and physical properties of Group IV elements for the current syllabus? (A2)

 

[qwertypoiu]

Q37 For a molecule to be in same plane it should have an angle of 120 degree in its compound
option A contains a 120 degree angle due to C=C bond.
I think option B have planar structure for it can also exist as cyclopropane which have angle of 120 degree.
From the examination report:
Question 37 The most commonly chosen incorrect answer was C. This suggests that most candidates knew that the three carbon atoms in propane all lie in the same plane. The six carbon atoms in 2,3-dimethylbut-2-ene also all lie in the same plane, since the bond angles at an sp2 hybridised carbon atom are very close to 120°, and the π bond prevents rotation. However, the six carbon atoms in cyclohexane do not lie in the same plane, they are all sp3 hybridised with bond angles close to 109°.

Propane has carbon atoms that lie on a plane because it only has three carbons. It is sp3 hybridised and has bond angles of 109, but the carbon atoms still lie in a plane because any three points in a three dimensional space can be placed on a single plane.

 

[Bishnu Dev]

When calculating Ecell, what is the correct method? Suppose that we have two standard electrode potential values: +1.32, -0.37
These two half cells were coupled together
In that case Ecell = 1.32-(-0.37)? or -0.37-1.32? mark scheme provides only one answer but i think it should differ depending on the terminals to which the voltmeter is connected. Any idea?

 

[anastasia grey113]

When calculating Ecell, what is the correct method? Suppose that we have two standard electrode potential values: +1.32, -0.37
These two half cells were coupled together
In that case Ecell = 1.32-(-0.37)? or -0.37-1.32? mark scheme provides only one answer but i think it should differ depending on the terminals to which the voltmeter is connected. Any idea?

Subtract the smaller one from the larger one.
The answer would be 1.32-(-0.37)