Login

Welcome, Guest. Please login or register.

July 24, 2025, 10:49:20 pm

Author Topic: QUick QuestioN!!  (Read 832 times)  Share 

0 Members and 1 Guest are viewing this topic.

man0005

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 228
  • Respect: +1
QUick QuestioN!!
« on: February 08, 2011, 06:50:02 pm »
0
Can someone explain to me what the unit gm/L is? regarding density
and whats the formula relating to density?

Mint

  • Guest
Re: QUick QuestioN!!
« Reply #1 on: February 08, 2011, 06:53:36 pm »
0
Density is m/v

man0005

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 228
  • Respect: +1
Re: QUick QuestioN!!
« Reply #2 on: February 08, 2011, 06:56:33 pm »
0
whats gm?

pi

  • Honorary Moderator
  • Great Wonder of ATAR Notes
  • *******
  • Posts: 14348
  • Doctor.
  • Respect: +2376
Re: QUick QuestioN!!
« Reply #3 on: February 08, 2011, 07:18:06 pm »
0
Sure its not g/mL instead?

man0005

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 228
  • Respect: +1
Re: QUick QuestioN!!
« Reply #4 on: February 08, 2011, 07:26:42 pm »
0
it says gmL^-1 :S

i'll give you whole question, easier for everyone ;)

The concentration of ethanol (C2H5OH) in a sample of Brandy is 4.8 M (mol/L). If the density of ethanol is 0.79 gmL^-1 , calculate the concentration of ethanol % (v/v) in the Brandy. (Assume 20 mL of Brandy)

pi

  • Honorary Moderator
  • Great Wonder of ATAR Notes
  • *******
  • Posts: 14348
  • Doctor.
  • Respect: +2376
Re: QUick QuestioN!!
« Reply #5 on: February 08, 2011, 07:29:56 pm »
0
That means g/mL  (think of it as g(mL)^-1)...

man0005

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 228
  • Respect: +1
Re: QUick QuestioN!!
« Reply #6 on: February 08, 2011, 07:30:56 pm »
0
oh really?
do they normally capitalise the L at the end? O_O
so confusing

chuck_norris

  • Guest
Re: QUick QuestioN!!
« Reply #7 on: February 08, 2011, 07:49:55 pm »
0
Yep L = litres and m is the milli prefix (1/1000)

So mL = 1 milli litre

It's not proper notation, as just gmL^-1 but it is so common that the parenthesis are left off.

But density is a measure of the mass per unit volume - the higher the density, the more "concentrated" or compact the substance is.

man0005

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 228
  • Respect: +1
Re: QUick QuestioN!!
« Reply #8 on: February 08, 2011, 07:59:45 pm »
0
oh okay
thanks for that guys :D

man0005

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 228
  • Respect: +1
Re: QUick QuestioN!!
« Reply #9 on: February 08, 2011, 09:24:35 pm »
0
if you guys have time, can you try the question and tell me what you get, so i can see if i did it right ;D

chuck_norris

  • Guest
Re: QUick QuestioN!!
« Reply #10 on: February 08, 2011, 09:47:22 pm »
0
The concentration of ethanol (C2H5OH) in a sample of Brandy is 4.8 M (mol/L). If the density of ethanol is 0.79 gmL^-1 , calculate the concentration of ethanol % (v/v) in the Brandy. (Assume 20 mL of Brandy)









(this is not a frequently used formula, but with stuff like this just look at the units - you have g and gmL^-1 and you want to end up with mL only so you go -- where v=volume; m=mass; d=density.)

So, as a percentage that is:

%% (2sf)
« Last Edit: February 08, 2011, 09:52:47 pm by chuck_norris »

man0005

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 228
  • Respect: +1
Re: QUick QuestioN!!
« Reply #11 on: February 08, 2011, 10:04:23 pm »
0
awesomeee, got the same :)
thanks for that

chuck_norris

  • Guest
Re: QUick QuestioN!!
« Reply #12 on: February 08, 2011, 10:08:55 pm »
0
No worries, man0005.