Chemical Forums

Please login or register.

Login with username, password and session length

Sponsored links

Pages: [1]   Go Down

Author Topic: Problem of the week - 27/05/2013  (Read 12483 times)

0 Members and 1 Guest are viewing this topic.

Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Mole Snacks: +1566/-390
  • Offline Offline
  • Gender: Male
  • Posts: 23764
  • I am known to be occasionally wrong.
    • Chembuddy
Problem of the week - 27/05/2013
« on: May 27, 2013, 12:39:20 AM »

What is the density of the sulfuric acid solution (g/mL) if its percent w/w concentration is 60.16% and w/v percent concentration is 90.24%?
Logged
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info

Schrödinger

  • Chemist
  • Sr. Member
  • *
  • Mole Snacks: +138/-98
  • Offline Offline
  • Gender: Male
  • Posts: 1159
Re: Problem of the week - 27/05/2013
« Reply #1 on: May 27, 2013, 05:56:20 PM »

bar cbvag svir g/mL?
Logged
"Destiny is not a matter of chance; but a matter of choice. It is not a thing to be waited for; it is a thing to be achieved."
- William Jennings Bryan

curiouscat

  • Chemist
  • Sr. Member
  • *
  • Mole Snacks: +121/-35
  • Offline Offline
  • Posts: 3005
Re: Problem of the week - 27/05/2013
« Reply #2 on: May 27, 2013, 06:45:47 PM »

[tex]
\LARGE{\sqrt[3]{3.375}}
[/tex]

g/ml
Logged

Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Mole Snacks: +1566/-390
  • Offline Offline
  • Gender: Male
  • Posts: 23764
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Problem of the week - 27/05/2013
« Reply #3 on: May 28, 2013, 05:57:43 AM »

Have you used density tables?
Logged
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info

Rutherford

  • Sr. Member
  • *****
  • Mole Snacks: +59/-29
  • Offline Offline
  • Gender: Male
  • Posts: 1866
Re: Problem of the week - 27/05/2013
« Reply #4 on: May 28, 2013, 06:25:42 AM »

I didn't.
ω(mass share)=mH2SO4/msolution=0.6016
φ(volume share)=VH2SO4/Vsolution=0.9024
Dividing:
ω/φ=Vsolution/msolution=0.6667
Vsolution=0.6667msolution
ρsolution=msolution/Vsolution=msolution/0.6667msolution=1.5gcm-3
Logged

curiouscat

  • Chemist
  • Sr. Member
  • *
  • Mole Snacks: +121/-35
  • Offline Offline
  • Posts: 3005
Re: Problem of the week - 27/05/2013
« Reply #5 on: May 28, 2013, 06:48:19 AM »

Have you used density tables?

Nope.
Logged

Schrödinger

  • Chemist
  • Sr. Member
  • *
  • Mole Snacks: +138/-98
  • Offline Offline
  • Gender: Male
  • Posts: 1159
Re: Problem of the week - 27/05/2013
« Reply #6 on: May 28, 2013, 06:48:50 AM »

Have you used density tables?
:O No!

It's a fairly simple question. If 100 g of the soln contains 60.16 g of H2SO4 and 100 mL of the solution contains 90.24 g of H2SO4, all one needs to find out is how many mL of soln corresponds to 60.16 g H2SO4, because this volume of soln which corresponds to 60.16 g of H2SO4, also weighs 100 g (given).
Logged
"Destiny is not a matter of chance; but a matter of choice. It is not a thing to be waited for; it is a thing to be achieved."
- William Jennings Bryan

Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Mole Snacks: +1566/-390
  • Offline Offline
  • Gender: Male
  • Posts: 23764
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Problem of the week - 27/05/2013
« Reply #7 on: May 28, 2013, 07:33:40 AM »

I know you don't have to. I was wondering how to word the question - whether to name the compound or not. If it is named, it suggests it is a specific case, not a general thing.
Logged
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info

Big-Daddy

  • Sr. Member
  • *****
  • Mole Snacks: +28/-94
  • Offline Offline
  • Posts: 1177
Re: Problem of the week - 27/05/2013
« Reply #8 on: May 30, 2013, 09:51:38 AM »

What's the justification for V[H2SO4]/m[H2SO4]=1?

Only then ρ[Solution]=Volume Share/Mass Share=1.500 g/cm3. Otherwise Volume Share/Mass Share=ρ[Solution]*V[H2SO4]/m[H2SO4].
Logged

curiouscat

  • Chemist
  • Sr. Member
  • *
  • Mole Snacks: +121/-35
  • Offline Offline
  • Posts: 3005
Re: Problem of the week - 27/05/2013
« Reply #9 on: May 30, 2013, 10:06:43 AM »

What's the justification for V[H2SO4]/m[H2SO4]=1?

Only then ρ[Solution]=Volume Share/Mass Share=1.500 g/cm3. Otherwise Volume Share/Mass Share=ρ[Solution]*V[H2SO4]/m[H2SO4].

density of solution is always equal to mass / volume.

The rest of what you wrote didn't make any sense to me. Especially not what "share" applies to.

Your equations don't even make dimensional sense.
Logged

Big-Daddy

  • Sr. Member
  • *****
  • Mole Snacks: +28/-94
  • Offline Offline
  • Posts: 1177
Re: Problem of the week - 27/05/2013
« Reply #10 on: May 30, 2013, 10:24:55 AM »

The rest of what you wrote didn't make any sense to me. Especially not what "share" applies to.

I was looking at Raderford's derivation as it is the only one on the page.

ω(mass share)=mH2SO4/msolution=0.6016
φ(volume share)=VH2SO4/Vsolution=0.9024

So there are the definitions of Mass Share and Volume Share.

Dividing:
ω/φ=Vsolution/msolution=0.6667

Look at the expressions for ω and φ; clearly ω/φ=mH2SO4·Vsolution/(msolution·VH2SO4). Only if mH2SO4/VH2SO4=1 does this reduce to ω/φ=Vsolution/msolution. What's the justification for that?
Logged

curiouscat

  • Chemist
  • Sr. Member
  • *
  • Mole Snacks: +121/-35
  • Offline Offline
  • Posts: 3005
Re: Problem of the week - 27/05/2013
« Reply #11 on: May 30, 2013, 10:27:36 AM »

He has a Typo. V should be m.
Logged

Big-Daddy

  • Sr. Member
  • *****
  • Mole Snacks: +28/-94
  • Offline Offline
  • Posts: 1177
Re: Problem of the week - 27/05/2013
« Reply #12 on: May 30, 2013, 11:22:17 AM »

He has a Typo. V should be m.

Ah I see. w/v. It's not volume fraction we want but mass concentration, so p[H2SO4]=m[H2SO4]/V[solution]. Got it now, thanks for the help.
Logged
Pages: [1]   Go Up
 

Mitch Andre Garcia's Chemical Forums 2003-Present.

Page created in 0.063 seconds with 24 queries.