# if you have the conc. of something......Watch

This discussion is closed.
#1
if you have the concentration of something in moldm-3 and gdm-3..... have do you find the mass from there???
0
13 years ago
#2
(Original post by Saf!)
if you have the concentration of something in moldm-3 and gdm-3..... have do you find the mass from there???
Is that 'grams per decimetre cubed'?

If so, then just muliply that by the volume in decimetres.
0
#3
yep is grams per decimetre cubed
but don't you do something like......moldm-3 divided by gdm-3???
0
13 years ago
#4
(Original post by Saf!)
yep is grams per decimetre cubed
but don't you do something like......moldm-3 divided by gdm-3???
That would give you moles per gram.
You could find the molecular mass by doing it the other way round though.
0
#5
oh..ok......thanx!
0
13 years ago
#6
Do you know the volume?
0
13 years ago
#7
You want to find the Mr ?
0
#8
(Original post by endeavour)
You want to find the Mr ?
yeh......that what i have to end up finding
0
13 years ago
#9
(Original post by Saf!)
yeh......that what i have to end up finding
Divide g dm^-3 by mol dm^-3.
0
13 years ago
#10
(Original post by Saf!)
yeh......that what i have to end up finding

0
#11
(Original post by Golden Maverick)
Divide g dm^-3 by mol dm^-3.
o.k thanx ................can i just ask .......why you have to do that... just so that i understand what i'm doing
0
#12
(Original post by endeavour)
oh right! thanx......but isn't it mol=vxc/1000
0
13 years ago
#13
(Original post by Saf!)
o.k thanx ................can i just ask .......why you have to do that... just so that i understand what i'm doing
Endeavour explaines it well. You basically are just dividing out the concentration factor. You need so divide out
0
13 years ago
#14
(Original post by Saf!)
oh right! thanx......but isn't it mol=vxc/1000
mol=vol*conc / 1000 when the volume is in cm^3. (ie divide by 1000 to convert to dm^3)
0
#15
(Original post by endeavour)
mol=vol*conc / 1000 when the volume is in cm^3. (ie divide by 1000 to convert to dm^3)
oh!
0
#16
thanx guys!......you both deserve rep and you'll get! .......(sometime this week...but i won't forget!)
0
X
new posts

Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

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

### University open days

• University of Lincoln
Wed, 12 Dec '18
• Bournemouth University
Midwifery Open Day at Portsmouth Campus Undergraduate
Wed, 12 Dec '18
• Buckinghamshire New University
Wed, 12 Dec '18

### Poll

Join the discussion

#### Do you like exams?

Yes (178)
18.78%
No (571)
60.23%
Not really bothered about them (199)
20.99%

View All
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

### See more of what you like onThe Student Room

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