Molecular ions Watch

Yatayyat
Badges: 14
Rep:
?
#1
Report Thread starter 10 months ago
#1
How do I do this? I don’t have a clue on what to do??

Thanks.

Name:  1C01CB79-D0B1-4341-8E7F-E4A9ED5DCEE6.jpg.jpeg
Views: 15
Size:  14.3 KB
Posted on the TSR App. Download from Apple or Google Play
0
reply
username3694440
Badges: 15
Rep:
?
#2
Report 10 months ago
#2
im guessing C, since the others all have oxygen in them and C doesn't
0
reply
Yatayyat
Badges: 14
Rep:
?
#3
Report Thread starter 10 months ago
#3
(Original post by hello2906)
im guessing C, since the others all have oxygen in them and C doesn't
But how does that explain the answer?
Posted on the TSR App. Download from Apple or Google Play
0
reply
LiiHyde
Badges: 14
Rep:
?
#4
Report 10 months ago
#4
(Original post by Yatayyat)
But how does that explain the answer?
It doesn't

By molecular ion - you know in the M/Z graphs they give you where you look at molecular ion peaks? The mass is determined by the largest mass recorded as the ion formed is simply the compound only missing 1 electron

so
A = C4H8O Which has a molecular mass of 72gmol-1
B = C4H7OH = 72gmol-1
C = C5H12 = 72gmol-1
D = C5H10O = 86gmol-1

Each molecule still has the same mass as it's molecular ion too
A simply forms C4H8O+ when an electron is knocked off
1
reply
username3694440
Badges: 15
Rep:
?
#5
Report 10 months ago
#5
(Original post by Yatayyat)
But how does that explain the answer?
is the answer C? Because all of the others are a collection of the same Cs and Hs, so will all have precisely the same molecular masses since theyre made up of exactly the same atoms. Oxygen has a slightly different mass to Cs/Hs, so the compound will have a slightly different Mr to the others.
0
reply
Yatayyat
Badges: 14
Rep:
?
#6
Report Thread starter 10 months ago
#6
(Original post by LiiHyde)
It doesn't

By molecular ion - you know in the M/Z graphs they give you where you look at molecular ion peaks? The mass is determined by the largest mass recorded as the ion formed is simply the compound only missing 1 electron

so
A = C4H8O Which has a molecular mass of 72gmol-1
B = C4H7OH = 72gmol-1
C = C5H12 = 72gmol-1
D = C5H10O = 86gmol-1

Each molecule still has the same mass as it's molecular ion too
A simply forms C4H8O+ when an electron is knocked off
Wait how does D have a mr of 86 isn’t 72?
Posted on the TSR App. Download from Apple or Google Play
0
reply
charco
  • Community Assistant
Badges: 17
Rep:
?
#7
Report 10 months ago
#7
The answer is C, because it is the only one without oxygen. All of the others have the same combination of carbon, hydrogen and oxygen. The precise Mr, i.e. down to six decimal places will be different for different molecular formula, even if the integral value appears the same.
0
reply
Yatayyat
Badges: 14
Rep:
?
#8
Report Thread starter 10 months ago
#8
(Original post by charco)
The answer is C, because it is the only one without oxygen. All of the others have the same combination of carbon, hydrogen and oxygen. The precise Mr, i.e. down to six decimal places will be different for different molecular formula, even if the integral value appears the same.
Ahh alright. Mr is always the same when it is a whole value but it down to many decimals it’s not exactly the same. Makes sense to me. Thanks man.🙂
Posted on the TSR App. Download from Apple or Google Play
0
reply
LiiHyde
Badges: 14
Rep:
?
#9
Report 10 months ago
#9
My mistake I miscounted the carbons in when I drew them out - sorry if I caused any confusion
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
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

  • Cardiff University
    Undergraduate Open Day Undergraduate
    Wed, 27 Mar '19
  • University of Portsmouth
    Postgraduate and Part-Time Open Evenings Postgraduate
    Wed, 27 Mar '19
  • Middlesex University London
    Postgraduate Open Evening Postgraduate
    Wed, 27 Mar '19

How old were you when you first saw porn?

I've never seen it (123)
21.03%
Before I was 12 (200)
34.19%
13 (91)
15.56%
14 (71)
12.14%
15 (40)
6.84%
16 (17)
2.91%
17 (6)
1.03%
18 (5)
0.85%
Between the ages of 19 - 24 (8)
1.37%
Over 25 (1)
0.17%
12 (23)
3.93%

Watched Threads

View All