Chemical Forums

Please login or register.

Login with username, password and session length

Sponsored links

Pages: [1]   Go Down

Author Topic: Molarity  (Read 1219 times)

0 Members and 1 Guest are viewing this topic.

peterschmidt3943

  • Regular Member
  • ***
  • Mole Snacks: +0/-0
  • Offline Offline
  • Posts: 61
Molarity
« on: March 13, 2018, 11:54:32 AM »

Hello,

why does 0,005 M of H2SO4 have 0,01 M of protones?
Logged

sjb

  • Global Moderator
  • Sr. Member
  • ***
  • Mole Snacks: +211/-41
  • Offline Offline
  • Gender: Male
  • Posts: 3339
Re: Molarity
« Reply #1 on: March 13, 2018, 12:08:01 PM »

Why do you think it doesn't? What is a proton?
Logged

peterschmidt3943

  • Regular Member
  • ***
  • Mole Snacks: +0/-0
  • Offline Offline
  • Posts: 61
Re: Molarity
« Reply #2 on: March 13, 2018, 12:11:31 PM »

Well, 0,005 M already describes how many moles it got per litre...

I dont understand why one has to calculate 0,005*2 in order to get to the moles/l of the protones in the molceule...
Logged

peterschmidt3943

  • Regular Member
  • ***
  • Mole Snacks: +0/-0
  • Offline Offline
  • Posts: 61
Re: Molarity
« Reply #3 on: March 13, 2018, 12:20:27 PM »

or to put it in different words: Why do I have to calculate the number of protones in a neutralisation reaction in oder to see to what extent it reacted with the base?? Why not calculate with 0,005 M?
Logged

Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Mole Snacks: +1607/-394
  • Offline Offline
  • Gender: Male
  • Posts: 24541
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Molarity
« Reply #4 on: March 13, 2018, 12:27:34 PM »

Well, 0,005 M already describes how many moles it got per litre...

Moles of what?
Logged
Chembuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info, PZWT_s1

peterschmidt3943

  • Regular Member
  • ***
  • Mole Snacks: +0/-0
  • Offline Offline
  • Posts: 61
Re: Molarity
« Reply #5 on: March 13, 2018, 12:34:28 PM »

H2SO4
Logged

Arkcon

  • Retired Staff
  • Sr. Member
  • *
  • Mole Snacks: +531/-146
  • Offline Offline
  • Posts: 7360
Re: Molarity
« Reply #6 on: March 13, 2018, 02:29:48 PM »

But you have  0,005 M of H2SO4, how come you seem to have twice as many molar of protons?  Did you double them somehow?  Look at the formula.
Logged
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

peterschmidt3943

  • Regular Member
  • ***
  • Mole Snacks: +0/-0
  • Offline Offline
  • Posts: 61
Re: Molarity
« Reply #7 on: March 13, 2018, 02:56:15 PM »

Hm? What do you mean exactly ?
Logged

jestearns

  • Regular Member
  • ***
  • Mole Snacks: +0/-0
  • Offline Offline
  • Gender: Male
  • Posts: 12
Re: Molarity
« Reply #8 on: March 13, 2018, 06:25:44 PM »

Your question involves stoichiometry.  Each molecule of sulfuric acid is diprotic (has 2 hydrogen atoms per molecule).  Therefore,

0.005 mol H2SO4/L * 2 mol H+/mol H2SO4 = 0.01 mol H+/L
Logged

peterschmidt3943

  • Regular Member
  • ***
  • Mole Snacks: +0/-0
  • Offline Offline
  • Posts: 61
Re: Molarity
« Reply #9 on: March 13, 2018, 08:49:30 PM »

is that the reason why a puffer based on 

10 ml of   0,1 M Phosphatpuffer and

100 ml of a 0,01 M Phosphatpuffer

consisting of the same amount of KH2PO4 und K2HPO4

can puffer the same amout of OH as well as H+ (because we would have 0,1*0,1 = 0,01 M protones in the first one; and since we got PO4 in the same amount, we have to calculate nothing here)

Why do they both have the same amount of electrolytes and difer in the concentration of the electrolytes?

Logged

peterschmidt3943

  • Regular Member
  • ***
  • Mole Snacks: +0/-0
  • Offline Offline
  • Posts: 61
Re: Molarity
« Reply #10 on: March 13, 2018, 09:25:51 PM »

and the reason why I was so confused about my initial question was that my prof calculated M of H+ * V =  0,1M of NaOH * V
in order to see if we got equimolar compounds... why didnt he go with 0,005 of the whole compund H2PO4? Why did he not calculate by the same token the M of OH we got in NaOH??
Logged

Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Mole Snacks: +1607/-394
  • Offline Offline
  • Gender: Male
  • Posts: 24541
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Molarity
« Reply #11 on: March 13, 2018, 09:50:35 PM »

H2SO4

And how many moles of H+ per mole of H2SO4?
Logged
Chembuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info, PZWT_s1

peterschmidt3943

  • Regular Member
  • ***
  • Mole Snacks: +0/-0
  • Offline Offline
  • Posts: 61
Re: Molarity
« Reply #12 on: March 14, 2018, 03:12:00 AM »

2
Logged
Pages: [1]   Go Up
 

Mitch Andre Garcia's Chemical Forums 2003-Present.

Page created in 0.059 seconds with 23 queries.