Chemistry: Post your doubts here!

[Metanoia]

Thnx............also is the cis - trans isomerism the same as EZ isomerism?

Cis-trans and EZ are both geometrical isomers but are not the same.

Cis-trans is more specific, it requires at least 2 out of the 4 groups (at the C=C) to be identical to each other. ClCH=CHCl or ClCH=CHBr

EZ is more general, it can consist of 4 different groups. ClCH3C=CHBr

 

[The Sarcastic Retard]

When I solve recent years past papers that is from 2007 to 2015(summer) summer and witner both I use to score always above 50. Now when I look into old years like this paper I ended up at the score of just 46. I have so many doubts in this paper. If anyone can help me out solving, Q1(c)(d), Q2(c)(d), Q5(c), Q7(b)(c) in Q7(b) arent answer in ms for uses of esters? Please do it as soon as possible. Also, When I was solving papers I found that mostly moles thingy are in summer papers, in winter papers its mostly inorganic part and theory. Am I correct? Should I expect 2015 november paper to be easier with moles thingy??

Thank you,
Regards,
XPC member,
The Sarcastic Retard

 

[sj0007]

Yea,the substituent gets named first, next the double bond, then hydroxyl group ...
But we number the carbons so that hydroxyl group gets the lowest number possible

Thanku sooo much!

 

[sj0007]

Cis-trans and EZ are both geometrical isomers but are not the same.

Cis-trans is more specific, it requires at least 2 out of the 4 groups (at the C=C) to be identical to each other. ClCH=CHCl or ClCH=CHBr

EZ is more general, it can consist of 4 different groups. ClCH3C=CHBr

Oooohkaaaayyy! I get it now.............thnx for replying and taking out ur time though.........

 

[awesomaholic101]

Thanku sooo much!

No problem

 

[talal096]

Any guess for the paper? Any particular topic which can come?

 

[awesomaholic101]

Any guess for the paper? Any particular topic which can come?

Lol ... How about organic chemistry? You'll never go wrong with that one.

 

[The Sarcastic Retard]

Lol ... How about organic chemistry? You'll never go wrong with that one.

Organic stuff is always easy

 

[awesomaholic101]

Organic stuff is always easy

I wouldn't say always ... Especially finding the no. of isomers and all is just plain annoying ... But otherwise its good ... Tricky, but good.

 

[The Sarcastic Retard]

I wouldn't say always ... Especially finding the no. of isomers and all is just plain annoying ... But otherwise its good ... Tricky, but good.

True that.

 

[lemonrsiow]

Can anyone explain to me why the potential of the electrode decreases as [Ag+] decreases?

1)b)ii)

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w05_qp_4.pdf

Shouldnt it increases because in Ag+ + e => Ag, decreasing Ag+ would shift equilibrium to LHS so increasing the Eo?

 

[The Sarcastic Retard]

When I solve recent years past papers that is from 2007 to 2015(summer) summer and witner both I use to score always above 50. Now when I look into old years like this paper I ended up at the score of just 46. I have so many doubts in this paper. If anyone can help me out solving, Q1(c)(d), Q2(c)(d), Q5(c), Q7(b)(c) in Q7(b) arent answer in ms for uses of esters? Please do it as soon as possible. Also, When I was solving papers I found that mostly moles thingy are in summer papers, in winter papers its mostly inorganic part and theory. Am I correct? Should I expect 2015 november paper to be easier with moles thingy??

Thank you,
Regards,
XPC member,
The Sarcastic Retard

No one knows this?? Metanoia awesomaholic101

 

[darks]

Anyone please give me "Average isotopic mass" definition & tollen's reagent result... is it "silvery mirror formed" or "silvery mirror ppt." ?

 

[The Sarcastic Retard]

Anyone please give me "Average isotopic mass" definition & tollen's reagent result... is it "silvery mirror formed" or "silvery mirror ppt." ?

From where did u got a phrase like Avg. isotopic mass?
The colourless solution produces a grey precipitate of silver, or a silver mirror on the test tube.

 

[darks]

From where did u got a phrase like Avg. isotopic mass?
The colourless solution produces a grey precipitate of silver, or a silver mirror on the test tube.

ok what about average atomic mass?
and thanks for clearing that tollen's problem.

 

[Sarosh Jameel]

PLZ someone explain me part III and IV ...

 

[awesomaholic101]

No one knows this?? Metanoia awesomaholic101

Sorry no idea ... I never really did many papers and when i did, i didn't focus on the pattern .... So i would like to know as well.

 

[The Sarcastic Retard]

Sorry no idea ... I never really did many papers and when i did, i didn't focus on the pattern .... So i would like to know as well.

Can u solve my doubts?

 

[The Sarcastic Retard]

ok what about average atomic mass?
and thanks for clearing that tollen's problem.

The average atomic mass of an element is the sum of the masses of its isotopes, each multiplied by its natural abundance

 

[darks]

The average atomic mass of an element is the sum of the masses of its isotopes, each multiplied by its natural abundance

divided by 100? thanks so we write as is?
my teacher was saying definitions like these will come.. so i'm just making sure.