Quick Question about a Concentration Problem

  • Thread starter Lori
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  • #1
Lori

Homework Statement



upload_2017-11-20_21-41-11.png

Homework Equations


M = n/1 L

The Attempt at a Solution


I was wondering if the answer is 6E. I'm not too sure about what the question is asking but i do know that the more moles there are, the more concetration of ions there will be. So, E seems like the answer since it has more atoms in the compounds. Is my logic correct?[/B]
 

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Answers and Replies

  • #2
DoItForYourself
Hi,

Practically, (in P=atmospheric and T=25°C) the dissociations that you need to take into consideration (compare) are B and C. Methanol (D) does not dissociate and acetic acid (E) dissociates only partially in water. Finally, BaSO4 (A) is not soluble in water.
 
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  • #3
Borek
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No need for Ksp here. At 1 mol/L you can safely assume both CaCl2 and NaNO3 to be fully soluble and BaSO4 to be not soluble at all. Then, it is just a matter of number of ions produced during dissociation (writing the dissociation reaction equation will help if you don't see it immediately).

CH3COOH is acetic acid (not an alcohol!). It definitely dissociates, but as it is a weak acid, only partially. Safe to assume no more than just few % will be dissociated (actually just a few tenths of a %).
 
  • #4
DoItForYourself
Sorry, my bad, of course acetic acid is not an alcohol.

Post #2 has been edited in order to be correct.
 
  • #5
Lori
No need for Ksp here. At 1 mol/L you can safely assume both CaCl2 and NaNO3 to be fully soluble and BaSO4 to be not soluble at all. Then, it is just a matter of number of ions produced during dissociation (writing the dissociation reaction equation will help if you don't see it immediately).

CH3COOH is acetic acid (not an alcohol!). It definitely dissociates, but as it is a weak acid, only partially. Safe to assume no more than just few % will be dissociated (actually just a few tenths of a %).
If I were to count the ions for CaCl2 would be be 3 ions? Because Cl disocciates into 2 ions
 
  • #6
Borek
Mentor
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3,254
If I were to count the ions for CaCl2 would be be 3 ions? Because Cl disocciates into 2 ions

Three ions, yes. Not sure what you mean by "Cl dissociates into two ions". There ARE two moles of Cl- ions per each CaCl2 mole, there is no "Cl" (nor "Cl2" for that matter) that can dissociate.
 
  • #7
Lori
Three ions, yes. Not sure what you mean by "Cl dissociates into two ions". There ARE two moles of Cl- ions per each CaCl2 mole, there is no "Cl" (nor "Cl2" for that matter) that can dissociate.
Oh. How would the acetic acid work. i could the ions
 
  • #8
Borek
Mentor
28,778
3,254
Oh. How would the acetic acid work. i could the ions

English please.

Acetic acid dissociates according to the equation

CH3COOH ↔ CH3COO- + H+

but it dissociates only partially (it is an equilibrium reaction, judging from your other questions something you have probably not yet heard about).
 

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