May 03, 2024, 01:17:50 AM
Forum Rules: Read This Before Posting


« previous next »
Pages: [1]   Go Down

Topic: Neutralising  (Read 6375 times)

0 Members and 1 Guest are viewing this topic.

Offline springgy

  • Regular Member
  • ***
  • Posts: 22
  • Mole Snacks: +0/-0
Neutralising
« on: December 08, 2007, 03:54:58 PM »
With the advice of Borek I decided to start a new thread

question about neutralising.

I've been told to work the volume needed to neutralise 100cm3 of my aspirin solution (0.011M, and 2.05pH) with calcium hydroxide.

Now so far I worked out the Molarity of my calcium hydroxide, which I got 0.125M, but when I did the pH of it I got something like 0.9. Now, don't you need a acid and a alkali to neutralise?

So I'm a bit clueless as to either what to do, or where I have gone wrong. I've looked through my books from A-level, but I can't find anything on this and google just throws about 1bzillion pages at me.

Cheers for any help
Logged

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 27669
  • Mole Snacks: +1801/-410
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Neutralising
« Reply #1 on: December 08, 2007, 04:02:28 PM »
Hint: pH or pOH?
Logged
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline springgy

  • Regular Member
  • ***
  • Posts: 22
  • Mole Snacks: +0/-0
Re: Neutralising
« Reply #2 on: December 08, 2007, 04:28:14 PM »
Just tried that now with the pOH.

I put in my calculator: -log0.125

and I still get 0.9, hmmm,

I'm doing: Moles = mass/Mr = 5g/40

=0.125

0.125/1 (my volume in litres) 0.125M

then doing -log0.125 = 0.9pH

That look about right for working out pH as we are not given proper values. Just says 5% weight by volume.
Logged

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 27669
  • Mole Snacks: +1801/-410
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Neutralising
« Reply #3 on: December 08, 2007, 05:43:25 PM »
What is pH definition? What is pOH definition? How they are related? What are products of Ca(OH)2 dissociation?
Logged
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline springgy

  • Regular Member
  • ***
  • Posts: 22
  • Mole Snacks: +0/-0
Re: Neutralising
« Reply #4 on: December 10, 2007, 01:09:14 PM »
Right, new info.

I have now worked out:

pH of Aspirin = 1.05
pOH of Calcium Hydroxide = 0.255
Asprin solution volume = 100cm3
Aspirin Molarity = 0.111
Ca(OH)2 Molarity = 0.0555

So, where do I go from here in order to work out the volume of Calcium Hydroxide needed to neutralise aspirin? I feel that I need to rearrange an equation to get a volume. But I dunno what equation.
Logged

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 27669
  • Mole Snacks: +1801/-410
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Neutralising
« Reply #5 on: December 10, 2007, 01:56:20 PM »
Are you sure you need anything more than just simple neutralization reaction and simple stoichiometry?

What is reaction equation?

How many moles of aspirin?
Logged
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline springgy

  • Regular Member
  • ***
  • Posts: 22
  • Mole Snacks: +0/-0
Re: Neutralising
« Reply #6 on: December 10, 2007, 02:17:42 PM »
Well, (I think) we have 0.0111moles of aspirin, and 0.067moles of calcium hydroxide.


So if that ratio is like 1:6, does that mean I only need 16.6cm3 of calcium hydroxide to neutralise it?
Logged

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 27669
  • Mole Snacks: +1801/-410
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Neutralising
« Reply #7 on: December 10, 2007, 03:40:05 PM »
Logged
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline springgy

  • Regular Member
  • ***
  • Posts: 22
  • Mole Snacks: +0/-0
Re: Neutralising
« Reply #8 on: December 10, 2007, 03:56:55 PM »
C9H804 + Ca(OH)2 ---> C9H6O4 + 2H2O

??

tHATS A WILD GUESS. I don't even know what I'm doing anymore.
Logged

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 27669
  • Mole Snacks: +1801/-410
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Neutralising
« Reply #9 on: December 10, 2007, 04:17:46 PM »
What is neutralisation?

How many acidic protons in aspirin?

What happened to Ca2+ in your equation?
Logged
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline springgy

  • Regular Member
  • ***
  • Posts: 22
  • Mole Snacks: +0/-0
Re: Neutralising
« Reply #10 on: December 10, 2007, 04:46:57 PM »
When an acid and a base react to give water and salt?

1?

The Ca2+ was suppose to be on the C9H6O4
Logged
Pages: [1]   Go Up
« previous next »
Sponsored Links