AS-Level Edexcel Chemistry Past papers Help. Watch

Kk1999
Badges: 2
Rep:
?
#1
Report Thread starter 3 years ago
#1
Hi,
Please help me solve these past-paper questions I have come Across.
I'll post a question and as I get a satisfied answer, I will post the next question.
There are 7 questions CURRENTLY.
Here is the First Question:
Name:  1.jpg
Views: 289
Size:  76.3 KB
0
reply
Dowel
Badges: 8
Rep:
?
#2
Report 3 years ago
#2
(Original post by Kk1999)
Hi,
Please help me solve these past-paper questions I have come Across.
I'll post a question and as I get a satisfied answer, I will post the next question.
There are 7 questions CURRENTLY.
Here is the First Question:
Name:  1.jpg
Views: 289
Size:  76.3 KB
Both are C
0
reply
Kk1999
Badges: 2
Rep:
?
#3
Report Thread starter 3 years ago
#3
(Original post by Dowel)
Both are C
How? Can u explain please?
0
reply
Sunethra
Badges: 5
Rep:
?
#4
Report 3 years ago
#4
(Original post by Kk1999)
Hi,
Please help me solve these past-paper questions I have come Across.
I'll post a question and as I get a satisfied answer, I will post the next question.
There are 7 questions CURRENTLY.
Here is the First Question:
Name:  1.jpg
Views: 289
Size:  76.3 KB
This is a very common and basic chemistry question. 1st one its C because as you go down a group the ionic radius increases because the number of shells down the group increases. The 2nd is also C because the greatest jump is btw the last two values thereofer its belong the group 4
1
reply
Dowel
Badges: 8
Rep:
?
#5
Report 3 years ago
#5
(Original post by Kk1999)
How? Can u explain please?
So the first one is about ionic radius. They all form a 2+ ion so that doesn't effect the trend in any way, as you go down the group there are more electron shells so the radius is bigger.

Second one the big gap is between 4-5 that means 4 electrons have been removed easily. The element must be in group 4 because this group forms 4+ ions easily but cannot form 5+ ions easily
1
reply
Kk1999
Badges: 2
Rep:
?
#6
Report Thread starter 3 years ago
#6
(Original post by Sunethra)
This is a very common and basic chemistry question. 1st one its C because as you go down a group the ionic radius increases because the number of shells down the group increases. The 2nd is also C because the greatest jump is btw the last two values thereofer its belong the group 4
So, Sunethra..u mean the answer should be found by looking for the greatest jump.
in question 2 the greatest jump is between 4400 (4th value) to 16100 (5th value).
the greatest jump was from 4 to 5 so the answer is Group 4.
Right
0
reply
Dowel
Badges: 8
Rep:
?
#7
Report 3 years ago
#7
(Original post by Kk1999)
So, Sunethra..u mean the answer should be found by looking for the greatest jump.
in question 2 the greatest jump is between 4400 (4th value) to 16100 (5th value).
the greatest jump was from 4 to 5 so the answer is Group 4.
Right
That's how you do it
0
reply
Kk1999
Badges: 2
Rep:
?
#8
Report Thread starter 3 years ago
#8
(Original post by Dowel)
That's how you do it
Thank you Dowel and Sunethra.
My next Question is:
Name:  2.jpg
Views: 262
Size:  10.1 KB
0
reply
Dowel
Badges: 8
Rep:
?
#9
Report 3 years ago
#9
(Original post by Kk1999)
Thank you Dowel and Sunethra.
My next Question is:
Name:  2.jpg
Views: 262
Size:  10.1 KB
Answer is B

You have C5H12 itself
You have 2-methyl butane
and 2,2 methyl propane
0
reply
Kk1999
Badges: 2
Rep:
?
#10
Report Thread starter 3 years ago
#10
(Original post by Dowel)
Answer is B

You have C5H12 itself
You have 2-methyl butane
and 2,2 methyl propane
C5H12 itself should be counted as an isomer?
and how do you know how many isomers are there??
any formula?
AND I HAVE PHY UNIT-1 TOMMOROW SO,
LL RETURN TO THE THREAD AFTER MY EXAM.
0
reply
Dowel
Badges: 8
Rep:
?
#11
Report 3 years ago
#11
(Original post by Kk1999)
C5H12 itself should be counted as an isomer?
and how do you know how many isomers are there??
any formula?
AND I HAVE PHY UNIT-1 TOMMOROW SO,
LL RETURN TO THE THREAD AFTER MY EXAM.
CHH12 is counted because it is a compound that has 5 carbons and 12 hydrogen's
you are looking for compounds that have 5 carbon and 12 hydrogen and pentane is one of them.

To work out how many isomers you need to try all the different possibilities, in this case their must be an isomer with a max carbon chain length of 4 and one with a max carbon length chain of 3 (two and one are impossible) and you need to add the last carbon into a position where it does not create a 5 carbon chain

So for example on the 4 carbon chain the methyl must go on the second carbon to achieve this and for the 3 carbon chain they must go on the central carbon.

Essentially your looking for any compounds that have the same number of carbon and hydrogen (same molecular formula) but have a different structural formula
0
reply
Kk1999
Badges: 2
Rep:
?
#12
Report Thread starter 3 years ago
#12
(Original post by Dowel)
CHH12 is counted because it is a compound that has 5 carbons and 12 hydrogen's
you are looking for compounds that have 5 carbon and 12 hydrogen and pentane is one of them.

To work out how many isomers you need to try all the different possibilities, in this case their must be an isomer with a max carbon chain length of 4 and one with a max carbon length chain of 3 (two and one are impossible) and you need to add the last carbon into a position where it does not create a 5 carbon chain

So for example on the 4 carbon chain the methyl must go on the second carbon to achieve this and for the 3 carbon chain they must go on the central carbon.

Essentially your looking for any compounds that have the same number of carbon and hydrogen (same molecular formula) but have a different structural formula
Two is not possible because...when we draw the isomers they look as if the chain is simply bent? Right?
0
reply
Dowel
Badges: 8
Rep:
?
#13
Report 3 years ago
#13
(Original post by Kk1999)
Two is not possible because...when we draw the isomers they look as if the chain is simply bent? Right?
Two isn't possible because if you try and draw it you find that the max chain length you can actually get is three. Remember that if you have something like this:

C-C
C

If you add any more carbons to that the chain lengths become > 2 and as we have five carbons we cannot not add any more carbons.
0
reply
Kk1999
Badges: 2
Rep:
?
#14
Report Thread starter 3 years ago
#14
(Original post by Dowel)
Two isn't possible because if you try and draw it you find that the max chain length you can actually get is three. Remember that if you have something like this:

C-C
C

If you add any more carbons to that the chain lengths become > 2 and as we have five carbons we cannot not add any more carbons.
Thank You Dowel...
My 3rd question is:
Name:  3.jpg
Views: 207
Size:  84.7 KB
0
reply
PlayerBB
Badges: 17
Rep:
?
#15
Report 3 years ago
#15
(Original post by Kk1999)
Thank You Dowel...
My 3rd question is:
Name:  3.jpg
Views: 207
Size:  84.7 KB
What exactly do you need help with in this question ?
0
reply
Kk1999
Badges: 2
Rep:
?
#16
Report Thread starter 3 years ago
#16
(Original post by PlayerBB)
What exactly do you need help with in this question ?
Sorry Sorry that i did not mention the part.
ITS PART B
0
reply
PlayerBB
Badges: 17
Rep:
?
#17
Report 3 years ago
#17
(Original post by Kk1999)
Sorry Sorry that i did not mention the part.
ITS PART B
You have to learn to practice to distinguish between these two reactions of alkanes, they're tricky but they'll earn you free marks

okay alkanes have two reactions which are similar to these two
  • Cracking: the heavy alkane (has a very long chain) is broken to produce a lighter alkane (has a shorter chain ) and an alkene
  • Reforming: The alkane is reformed to a benzene or to a cyclohexane + H2
It's supposed that is easier now, the first involves the formation of an alkene so it is Cracking and the second involves the formation of a benzene so it is reforming
1
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts

All the exam results help you need

2,746

people online now

225,530

students helped last year
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

University open days

  • University of Dundee
    Undergraduate Open Day Undergraduate
    Mon, 26 Aug '19
  • University of Aberdeen
    General Open Day Undergraduate
    Tue, 27 Aug '19
  • Norwich University of the Arts
    Postgraduate (MA) Open Day Postgraduate
    Sat, 31 Aug '19

How are you feeling about GCSE Results Day?

Hopeful (158)
13.28%
Excited (106)
8.91%
Worried (218)
18.32%
Terrified (278)
23.36%
Meh (94)
7.9%
Confused (32)
2.69%
Putting on a brave face (155)
13.03%
Impatient (149)
12.52%

Watched Threads

View All