December 23, 2024, 03:07:40 PM
Forum Rules: Read This Before Posting


Topic: spectrometry  (Read 2647 times)

0 Members and 2 Guests are viewing this topic.

Offline johnnyjohn993123

  • Regular Member
  • ***
  • Posts: 57
  • Mole Snacks: +0/-0
spectrometry
« on: July 08, 2016, 02:16:36 AM »
Pipet 2.50 mL of the iron solution into five large test tubes. Add 2.50 mL of
the acetate buffer, 0.50 mL of the hydroxylamine hydrochloride solution and
mix. Pipet 0.50, 1.00, 1.50, 2.00 and 2.50 mL of the 5.00 x10-4 M
phenanthroline solution. Dilute to a total volume of 15 mL with water. Stand
for 10 min then measure absorbance.
*Iron solution conc= 5.0x10-4M

Repeat procedure except that you should use 5.00 mL of 1.50 x10-3 M
phenanthroline solution and 0.25, 0.50, 0.75, 1.00 and 1.25 mL of the iron
solution.

Plot absorbance versus iron concentration (M) and absorbance versus

phenanthroline concentration (M). From the slopes of these 2 graphs,

calculate stoichiometry.

I dont get why find the slope when the concentration here is constant in both graphs , or I just miss interpret this ? Help

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 27887
  • Mole Snacks: +1815/-412
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: spectrometry
« Reply #1 on: July 08, 2016, 02:42:56 AM »
I dont get why find the slope when the concentration here is constant in both graphs

It is not. You use different amounts of substances to make the solutions, so the concentrations can't be constant.
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline johnnyjohn993123

  • Regular Member
  • ***
  • Posts: 57
  • Mole Snacks: +0/-0
Re: spectrometry
« Reply #2 on: July 08, 2016, 06:26:47 AM »
I dont get why find the slope when the concentration here is constant in both graphs

It is not. You use different amounts of substances to make the solutions, so the concentrations can't be constant.

OMG !! YOUR RIGHT! I didnt notice ! :D
 
but now I've plotted it, I had to use the linear correlation thingy and my slope ended having 3,108 ? why do you think so ...

Offline Arkcon

  • Retired Staff
  • Sr. Member
  • *
  • Posts: 7367
  • Mole Snacks: +533/-147
Re: spectrometry
« Reply #3 on: July 08, 2016, 08:39:12 PM »
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Sponsored Links