Author Topic: CHEM AND BIO HELP AND TIPS HERE  (Read 333270 times)

Offline WARRIOR

  • SF Master
  • ******
  • Posts: 1473
  • Reputation: 51196
  • Egyptian And so damn proud . I love you jesus!
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2805 on: June 06, 2010, 02:13:13 pm »
Got a doubt from the 2005 m/j paper 3 chemistry paper.
When 0.015 moles of iodine react with 0.045 moles of chlorine to form 0.030 moles of a single product. So, we have to complete the equation. The answer is:
I2 + 3Cl2 = 2ICl3                my question is how come theres 3 atms of Cl formed?

Oh and second question....when iodine reacts with zinc nd wen u decrease the concentration of iodine how come less of zinc is used up?

sincec ration is 1 : 3 : 2


and we normally get ICL

but since it is 2 ICL , we have have now 2 i odines and 2 chlorines

now we have to balance , 2 iodines on the left :D

but thre are 6 clhorines on the left and honly two on the right , so we have to change the cl into CL3


less concentraion = less molecules per unite volume , less molecules = less reaction , so less zinc gets used up
NO secrets to SUCCESS , it is the result of 1.HARD WORK 2.GOOD PREPARATION 3.LEARNING FROM FAILURE
But it ain't how hard you hit; it's about how hard you can get hit, and keep moving forward-Balboa

Offline Helium

  • SF Citizen
  • ***
  • Posts: 216
  • Reputation: 672
  • Knowledge is light
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2806 on: June 06, 2010, 02:14:26 pm »
Guys, a silly doubt :P Whats the difference between Heat, Roast and burn in air.. ??? Thanks.

All the same......
Aiming for the top

Offline WARRIOR

  • SF Master
  • ******
  • Posts: 1473
  • Reputation: 51196
  • Egyptian And so damn proud . I love you jesus!
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2807 on: June 06, 2010, 02:16:21 pm »
The polymer formed by HO-CH2CH2-OH and
HOOC-C6H4-COOH shouldnt it be OC-C6H4-COO-CH2CH2-O ?
The alcohol looses H and the acid looses - OH
The MS says :
-OOC-C6H4-COOCH2CH2O- =_="
Where did the first extra O come from >_> or its just a part of the last monomer?
the alcohol jst loses an H

which paper ?
NO secrets to SUCCESS , it is the result of 1.HARD WORK 2.GOOD PREPARATION 3.LEARNING FROM FAILURE
But it ain't how hard you hit; it's about how hard you can get hit, and keep moving forward-Balboa

Offline rhea

  • SF Immigrant
  • **
  • Posts: 66
  • Reputation: 82
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2808 on: June 06, 2010, 02:18:55 pm »
3..Ca+.2..Sc3+  -->  3...Ca2+ +.2..Sc


there has to be same maount of electrons on each side , therefore we make it 6 -->6
umm...but 2 on Sc when its valency is 3??!

i just dont get this ionic eq balancing!

Offline mdwael

  • SF Immigrant
  • **
  • Posts: 115
  • Reputation: 144
  • Gender: Male
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2809 on: June 06, 2010, 02:19:23 pm »
In may/june 2003 paper 3 chemistry how do you draw the structure of the polymer? its questions 3d(ii)
"We all want to be different, which makes us all the same"

Offline MasterMath

  • SF Citizen
  • ***
  • Posts: 233
  • Reputation: 329
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2810 on: June 06, 2010, 02:19:46 pm »
the alcohol jst loses an H

which paper ?
errm let me see . 2004 nov!

Offline WARRIOR

  • SF Master
  • ******
  • Posts: 1473
  • Reputation: 51196
  • Egyptian And so damn proud . I love you jesus!
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2811 on: June 06, 2010, 02:20:56 pm »
umm...but 2 on Sc when its valency is 3??!

i just dont get this ionic eq balancing!
its 3+  on th eleft  and 2 +  on the right , so we have to make it 6 to balance

so times 3+ by 2  and 2 + by 3 = 6

and snce now you have 2 SC 3+ oyu have to 2 SC atoms!
NO secrets to SUCCESS , it is the result of 1.HARD WORK 2.GOOD PREPARATION 3.LEARNING FROM FAILURE
But it ain't how hard you hit; it's about how hard you can get hit, and keep moving forward-Balboa

Offline WARRIOR

  • SF Master
  • ******
  • Posts: 1473
  • Reputation: 51196
  • Egyptian And so damn proud . I love you jesus!
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2812 on: June 06, 2010, 02:22:30 pm »
errm let me see . 2004 nov!
the C00 is a double bond

its right
NO secrets to SUCCESS , it is the result of 1.HARD WORK 2.GOOD PREPARATION 3.LEARNING FROM FAILURE
But it ain't how hard you hit; it's about how hard you can get hit, and keep moving forward-Balboa

Offline rhea

  • SF Immigrant
  • **
  • Posts: 66
  • Reputation: 82
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2813 on: June 06, 2010, 02:22:47 pm »
its 3+  on th eleft  and 2 +  on the right , so we have to make it 6 to balance

so times 3+ by 2  and 2 + by 3 = 6

and snce now you have 2 SC 3+ oyu have to 2 SC atoms!


ohkk!

got it!

thanks!

+rep!  ;)

Offline WARRIOR

  • SF Master
  • ******
  • Posts: 1473
  • Reputation: 51196
  • Egyptian And so damn proud . I love you jesus!
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2814 on: June 06, 2010, 02:23:54 pm »
In may/june 2003 paper 3 chemistry how do you draw the structure of the polymer? its questions 3d(ii)

link please
NO secrets to SUCCESS , it is the result of 1.HARD WORK 2.GOOD PREPARATION 3.LEARNING FROM FAILURE
But it ain't how hard you hit; it's about how hard you can get hit, and keep moving forward-Balboa

Offline MasterMath

  • SF Citizen
  • ***
  • Posts: 233
  • Reputation: 329
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2815 on: June 06, 2010, 02:25:17 pm »
the C00 is a double bond

its right
How is it correct O_O .. The acid looses -OH .. which makes it -OC ? im quiet sure..
I know that there is a double bond between the C and O but that doesnt mean there is 2x O .. its -OC ?

elemis

  • Guest
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2816 on: June 06, 2010, 02:27:40 pm »
How is it correct O_O .. The acid looses -OH .. which makes it -OC ? im quiet sure..
I know that there is a double bond between the C and O but that doesnt mean there is 2x O .. its -OC ?

TELL US WHICH YEAR THIS IS FROM !!!!

Offline MasterMath

  • SF Citizen
  • ***
  • Posts: 233
  • Reputation: 329
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2817 on: June 06, 2010, 02:28:24 pm »
How is it correct O_O .. The acid looses -OH .. which makes it -OC ? im quiet sure..
I know that there is a double bond between the C and O but that doesnt mean there is 2x O .. its -OC ?
If anyone can help here ? look at my question:
The polymer formed by HO-CH2CH2-OH and
HOOC-C6H4-COOH shouldnt it be OC-C6H4-COO-CH2CH2-O ?
The alcohol looses H and the acid looses - OH
The MS says :
-OOC-C6H4-COOCH2CH2O- =_="
Where did the first extra O come from >_> or its just a part of the last monomer?

Confirm whos correct please :)
asap :P

Offline MasterMath

  • SF Citizen
  • ***
  • Posts: 233
  • Reputation: 329
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2818 on: June 06, 2010, 02:28:55 pm »

TELL US WHICH YEAR THIS IS FROM !!!!

I think ive posted which year >_> 2004 nov =_="

Offline WARRIOR

  • SF Master
  • ******
  • Posts: 1473
  • Reputation: 51196
  • Egyptian And so damn proud . I love you jesus!
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2819 on: June 06, 2010, 02:29:10 pm »
How is it correct O_O .. The acid looses -OH .. which makes it -OC ? im quiet sure..

DRAW IT

-C0 is a double bond and it bonds to an 0

i always draw it i dotn like tht funny formula
NO secrets to SUCCESS , it is the result of 1.HARD WORK 2.GOOD PREPARATION 3.LEARNING FROM FAILURE
But it ain't how hard you hit; it's about how hard you can get hit, and keep moving forward-Balboa