Chemistry: Post your doubts here!

VelaneDeBeaute · Nov 25, 2012

Mayedah said:
if u have ethanal COHCOH
wht different isomers u can make out of the formula C2H2O2 such tht the isomer reacts with Na metal to form hydrogen ?

Should be an acid, or an alcohol!

Mayedah · Nov 26, 2012

VelaneDeBeaute said:
Should be an acid, or an alcohol! [/quote
yeah it should be an alcohol because only thn it will form H2 but i wanna know whether we can make triple bond between Carbon and carbon and 2 alcohol groups on both sides ?

VelaneDeBeaute · Nov 26, 2012

Yes, you can!

!>@/^~^\@<! · Nov 29, 2012

XPFMember said:
Hi everyone, AsSalamoAlaikum Wr Wb..

To get things organized in a better way, I am making this thread. As othewise, some queries remain unanswered!

So post your CHEMISTRY doubts in this thread. InshaAllah members around will help you.

Any Chemistry related notes and links will be added here in this post. Feel free to provide the links to your notes around the forum, or any other websites!

Chemistry Notes:

http://www.chemguide.co.uk This is the website, which contains almost everything classified according to the syllabus.

Tips for solving chemistry MCQs 9701/01

Chemistry P5 Tips and Notes

Some links & Notes - by 'destined007'

Chemistry worksheets Link shared by hassam

Chemistry Application Booklet: Mistakes and Corrections!

Calculations for A level Chemistry, author E.N. Ramsden third edition ebook download.

Regards,
XPC Staff.

Can u tell me the difference between the combustion reaction of "alkanes" and "alkenes"...??

iKhaled · Nov 29, 2012

!>@/^~^\@<! said:
Can u tell me the difference between the combustion reaction of "alkanes" and "alkenes"...??

is there a different? Oo i think all combustion of hydrocarbons r the same!

VelaneDeBeaute · Nov 29, 2012

!>@/^~^\@<! said:
Can u tell me the difference between the combustion reaction of "alkanes" and "alkenes"...??

There ain't any difference. Carbondioxide and water are produced in both cases. Just be careful with the balancing of the equations!

ZohaibAsad · Nov 29, 2012

VelaneDeBeaute said:
There ain't any difference. Carbondioxide and water are produced in both cases. Just be careful with the balancing of the equations!

!>@/^~^\@<! said:
Can u tell me the difference between the combustion reaction of "alkanes" and "alkenes"...??

Yep, CO2 and H20 are the products in both cases however the only difference is that the moles of H20 produced are different simply because of the fact that the number of hydrogen atoms differ, so burning ethane will produce more moles of H20 than ethene

!>@/^~^\@<! · Nov 30, 2012

Thanks, i know this, what is was trying to ask was that there was written something like this in a book:
"Like alkanes, alkenes burn to give H2O + CO2. However alkenes contain more carbon in proportion to hydrogen than do alkanes. This means that they need relatively more oxygen to burn completely than do alkanes."
What i don't get is that if we look at the equations of ethane and ethene, ethane needs more oxygen for combustion completely than ethene.
Ch3-CH3 + 7O2 .......> 2CO2 + 3H2O

CH2=CH2 + 6O2 ........> 2CO2 + 2H2O

So this shows that the amount of oxygen needed for combustion depends on the no. of hydrogen atoms present...
Am I correct....???

Lyfroker · Nov 30, 2012

what is the main type of bonding that holds the alkanes and alcohols together in their solid or liquid states?

!>@/^~^\@<! · Dec 1, 2012

XPFMember said:
Hi everyone, AsSalamoAlaikum Wr Wb..

To get things organized in a better way, I am making this thread. As othewise, some queries remain unanswered!

So post your CHEMISTRY doubts in this thread. InshaAllah members around will help you.

Any Chemistry related notes and links will be added here in this post. Feel free to provide the links to your notes around the forum, or any other websites!

Chemistry Notes:

http://www.chemguide.co.uk This is the website, which contains almost everything classified according to the syllabus.

Tips for solving chemistry MCQs 9701/01

Chemistry P5 Tips and Notes

Some links & Notes - by 'destined007'

Chemistry worksheets Link shared by hassam

Chemistry Application Booklet: Mistakes and Corrections!

Calculations for A level Chemistry, author E.N. Ramsden third edition ebook download.

Regards,
XPC Staff.

There was something written like this in a book:

"Like alkanes, alkenes burn to give H2O + CO2. However alkenes contain more carbon in proportion to hydrogen than do alkanes. This means that they need relatively more oxygen to burn completely than do alkanes."

What i don't get is that if we look at the equations of ethane and ethene, ethane needs more oxygen for complete combustion than ethene.
Ch3-CH3 + 7O2 ..........> 2CO2 + 3H2O

CH2=CH2 + 6O2 ........> 2CO2 + 2H2O

So this shows that the amount of oxygen needed for combustion depends on the no. of hydrogen atoms present not the ratio of carbon to hydrogen...!!
Am I correct....???

!>@/^~^\@<! · Dec 1, 2012

XPFMember said:
Hi everyone, AsSalamoAlaikum Wr Wb..

To get things organized in a better way, I am making this thread. As othewise, some queries remain unanswered!

So post your CHEMISTRY doubts in this thread. InshaAllah members around will help you.

Any Chemistry related notes and links will be added here in this post. Feel free to provide the links to your notes around the forum, or any other websites!

Chemistry Notes:

http://www.chemguide.co.uk This is the website, which contains almost everything classified according to the syllabus.

Tips for solving chemistry MCQs 9701/01

Chemistry P5 Tips and Notes

Some links & Notes - by 'destined007'

Chemistry worksheets Link shared by hassam

Chemistry Application Booklet: Mistakes and Corrections!

Calculations for A level Chemistry, author E.N. Ramsden third edition ebook download.

Regards,
XPC Staff.

In David Acaster its written that the tertiary carbocations are more stable than the primary carbocations. Alkyl groups tend to release electrons to atoms attached to them. Therefore a tertiary carbocation has three alkyl groups donating electrons towards the positively charged carbon atom, reducing its charge density. This makes it more stable than a primary carbocation.
But in E.N. Ramsdan its written that the tertiary carbocation is very unstable and reactive, so the second step is fast. No reason mentioned for it being unstable.

The tertiary carbocation is Stable or UNstable....???
Please Reply!!

XPFMember · Dec 1, 2012

!>@/^~^\@<! said:
In David Acaster its written that the tertiary carbocations are more stable than the primary carbocations. Alkyl groups tend to release electrons to atoms attached to them. Therefore a tertiary carbocation has three alkyl groups donating electrons towards the positively charged carbon atom, reducing its charge density. This makes it more stable than a primary carbocation.
But in E.N. Ramsdan its written that the tertiary carbocation is very unstable and reactive, so the second step is fast. No reason mentioned for it being unstable.

The tertiary carbocation is Stable or UNstable....???
Please Reply!!

AsSalamoAlaikum Wr Wb,

http://www.chemguide.co.uk/mechanisms/eladd/carbonium.html#top

^Check this..

So we come to the conclusion that tertiary carbo cation is relatively more stable than the primary or secondary one.

!>@/^~^\@<! · Dec 1, 2012

XPFMember said:
AsSalamoAlaikum Wr Wb,

http://www.chemguide.co.uk/mechanisms/eladd/carbonium.html#top

^Check this..

So we come to the conclusion that tertiary carbo cation is relatively more stable than the primary or secondary one.

So i shouldn't read E.N. Ramsdan because there are errors in it...???

!>@/^~^\@<! · Dec 1, 2012

XPFMember said:
AsSalamoAlaikum Wr Wb,

http://www.chemguide.co.uk/mechanisms/eladd/carbonium.html#top

^Check this..

So we come to the conclusion that tertiary carbo cation is relatively more stable than the primary or secondary one.

Thanks, can u ans this ques as well

There was something written like this in a book:

"Like alkanes, alkenes burn to give H2O + CO2. However alkenes contain more carbon in proportion to hydrogen than do alkanes. This means that they need relatively more oxygen to burn completely than do alkanes."

What i don't get is that if we look at the equations of ethane and ethene, ethane needs more oxygen for complete combustion than ethene.
Ch3-CH3 + 7O2 ..........> 2CO2 + 3H2O

CH2=CH2 + 6O2 ........> 2CO2 + 2H2O

So this shows that the amount of oxygen needed for combustion depends on the no. of hydrogen atoms present not the ratio of carbon to hydrogen...!!
Am I correct....???

ZohaibAsad · Dec 1, 2012

!>@/^~^\@<! said:
So i shouldn't read E.N. Ramsdan because there are errors in it...???

Well the thing is since CIE endorses their own book they won't leave any space for errors due to the material contained in it so technically you should stick to it.

!>@/^~^\@<! · Dec 2, 2012

ZohaibAsad said:
Well the thing is since CIE endorses their own book they won't leave any space for errors due to the material contained in it so technically you should stick to it.

Ok, Thanks!!

VelaneDeBeaute · Dec 2, 2012

!>@/^~^\@<! said:
Thanks, can u ans this ques as well

There was something written like this in a book:

"Like alkanes, alkenes burn to give H2O + CO2. However alkenes contain more carbon in proportion to hydrogen than do alkanes. This means that they need relatively more oxygen to burn completely than do alkanes."

What i don't get is that if we look at the equations of ethane and ethene, ethane needs more oxygen for complete combustion than ethene.
Ch3-CH3 + 7O2 ..........> 2CO2 + 3H2O

CH2=CH2 + 6O2 ........> 2CO2 + 2H2O

So this shows that the amount of oxygen needed for combustion depends on the no. of hydrogen atoms present not the ratio of carbon to hydrogen...!!
Am I correct....???

"Burning completely" mean "less side reactions", not how much oxygen it requires. Most things, when reacted with oxygen will not simply pour out water and CO2. You're going to get a lot of side products (carbon monoxide being one) and a lot of unreacted hydrocarbon, simply because of the nature of the reactants. So, just remember, that more oxygen needs to be supplied to the alkene to make it burn completely, irrespective of how much it uses.
I hope that tends to satisfy!

!>@/^~^\@<! · Dec 3, 2012

VelaneDeBeaute said:
"Burning completely" mean "less side reactions", not how much oxygen it requires. Most things, when reacted with oxygen will not simply pour out water and CO2. You're going to get a lot of side products (carbon monoxide being one) and a lot of unreacted hydrocarbon, simply because of the nature of the reactants. So, just remember, that more oxygen needs to be supplied to the alkene to make it burn completely, irrespective of how much it uses.
I hope that tends to satisfy!

Thanks, Yeah i does Help!! :-D

Soldier313 · Dec 3, 2012

Aoa wr wb
Can someone please help me with this qn

i need a detailed explanation please, for both parts i and ii)
tx a million.

A star · Dec 4, 2012

!>@/^~^\@<! said:
So i shouldn't read E.N. Ramsdan because there are errors in it...???

yeah you will never find any thing wrong but it will never contain every single information you need

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Chemistry: Post your doubts here!

VelaneDeBeaute

Mayedah

VelaneDeBeaute

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iKhaled

VelaneDeBeaute

ZohaibAsad

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Lyfroker

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XPFMember

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ZohaibAsad

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VelaneDeBeaute

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Soldier313

A star

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