Chemistry: Post your doubts here!

[A*****]

We take S8

Well the graph should not have shown 1.5 moles of oxygen then

 

[Ebrahim12]

Help And Explain.View attachment 64030 View attachment 64031 View attachment 64032

q18.
A) NH4+ does not NH3
B) NH3 is the one that accepts the H+
C) Changes from 107 in NH3 to 109.5 in NH4+, since NH4+ has a tetrahedral arrangement
D) This is the correct answer. H+ doesn't have any electrons, the bond is dative

Look at the mechanism to understand this better.

q4.
Only C has Hydrogen bonding which is stronger than the induce/permanent dipole IMFs of the other options.

q37.
Here's the mechanism:

Clearly 1 and 3 are correct, so the answer is A. I'm not sure what 2 is referencing exactly but I guess it's the collision between the OH ion and the haloalkane.

 

[Kanekii]

Help Needed urgent

Attacks on CH3, CH3CH2 and CH2
therefore 3 'B'

 

[Hisham Khan]

 

[Kanekii]

th

q18.
A) NH4+ does not NH3
B) NH3 is the one that accepts the H+
C) Changes from 107 in NH3 to 109.5 in NH4+, since NH4+ has a tetrahedral arrangement
D) This is the correct answer. H+ doesn't have any electrons, the bond is dative

Look at the mechanism to understand this better.

q4.
Only C has Hydrogen bonding which is stronger than the induce/permanent dipole IMFs of the other options.

q37.
Here's the mechanism:
View attachment 64036
Clearly 1 and 3 are correct, so the answer is A. I'm not sure what 2 is referencing exactly but I guess it's the collision between the OH ion and the haloalkane.

thank you

 

[Kanekii]

View attachment 64025
help?

HEATED
S8 is a simple molecular structure so its bonds broken..

 

[Ebrahim12]

Help and ExplainView attachment 64033 View attachment 64034

q22.
Sketch the products when the hot Mno42-/H+ breaks the double bonds:
A) forms an acid and a ketone
B) forms two different acids
C) forms a dicarboxylic acid (two co2h gps attached to the same molecule)
D) forms two acids but they have the same formula

answer is B

 

[Kanekii]

View attachment 64038 View attachment 64038 View attachment 64038 View attachment 64038 View attachment 64038 View attachment 64038 View attachment 64038 View attachment 64038 View attachment 64038

i have imaginary ceo friend of caies he says S8 is wrong...laahh

 

[Kanekii]

q22.
Sketch the products when the hot Mno42-/H+ breaks the double bonds:
A) forms an acid and a ketone
B) forms two different acids
C) forms a dicarboxylic acid (two co2h gps attached to the same molecule)
D) forms two acids but they have the same formula

answer is B

how B forms two different acids but D doesnt?
thank you so much for your help

 

[Ebrahim12]

how B forms two different acids but D doesnt?
thank you so much for your help

Imagine a line through the double bond in D, see how the previously double bonded carbon atoms are attached to the same group? both will form 2-methypropanoicacid. While in B they are attached to different groups.

 

[Mts.99]

what are electrodes made out of in electrolysis of brine?

 

[Tajrina Promela]

Why is the answer C?

 

[Hisham Khan]

what are electrodes made out of in electrolysis of brine?

Electrolyisis is not in As 2018 syllabus

 

[Hisham Khan]

i have imaginary ceo friend of caies he says S8 is wrong...laahh

I have never said S8 was wrong.What??
And the teacher is Mr Faiz.You can check him on facebook if you think I was beingg a liar like seriously tf dude??

 

[Hamnah Zahoor]

Plz can u explain those 2 qs?

I am sorry I just went offline minutes before you asked me but still I beleive I am not late
Q: 1 you asked is solved at the following website
http://chem-solutions-9701.blogspot.com/2016/11/chemistry-doubts-970111mj14.html
2 moles of a single product is formed just divide the formula of compound by 2
For question :2
For greatest amount of energy to be released the compound should not have oxygen in it or least amount for maximum energy released.
From examination report:
Question 9 Candidates were given four compounds – CH3CH2CH3 and three of its oxidation products, CH3CH2CH2OH, CH3COCH3 and CH3CH2CO2H – and asked which would release the greatest amount of energy on complete combustion. 40% of candidates gave the correct answer (propane itself), the others presumably not appreciating that every stage in the oxidation process would be exothermic, and that therefore the earliest point in a sequence of oxidations would yield the highest energy release. An alternative approach to this question would have been to make use of the table of bond energies within the Data Booklet, leading to the same conclusion. Rather surprisingly four questions had a facility below the design limit of 25%, i.e. below the ‘guessing level’, and the reasons for this were clearly very varied.

 

[Hisham Khan]

Isin't the answer D?

 

[A*****]

I am sorry I just went offline minutes before you asked me but still I beleive I am not late
Q: 1 you asked is solved at the following website
http://chem-solutions-9701.blogspot.com/2016/11/chemistry-doubts-970111mj14.html
2 moles of a single product is formed just divide the formula of compound by 2
For question :2
For greatest amount of energy to be released the compound should not have oxygen in it or least amount for maximum energy released.
From examination report:
Question 9 Candidates were given four compounds – CH3CH2CH3 and three of its oxidation products, CH3CH2CH2OH, CH3COCH3 and CH3CH2CO2H – and asked which would release the greatest amount of energy on complete combustion. 40% of candidates gave the correct answer (propane itself), the others presumably not appreciating that every stage in the oxidation process would be exothermic, and that therefore the earliest point in a sequence of oxidations would yield the highest energy release. An alternative approach to this question would have been to make use of the table of bond energies within the Data Booklet, leading to the same conclusion. Rather surprisingly four questions had a facility below the design limit of 25%, i.e. below the ‘guessing level’, and the reasons for this were clearly very varied.

Tysm but can u guide me a lil bit more regarding q2 using bond energies, how we will determine that? The extra C-H bond has the smallest value so what does it mean?

 

[A*****]

View attachment 64042
Isin't the answer D?

It is B...2nd is also correct since it is an anti oxidant

 

[Hisham Khan]

It is B...2nd is also correct since it is an anti oxidant

yes it does remove sour taste but I have schemes with this not as correct only anti oxidizing or reducing property and stop growth of aerobic bacteria are considered correct toh

 

[A*****]

How did it go guyz?