Find the [H3O+], [OH‐], pH, and pOH

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Discussion Overview

The discussion centers around calculating the concentrations of [H3O+], [OH-], pH, and pOH for a solution of Sr(OH)2 at a concentration of 0.1475 M. Participants explore the dissociation of the compound and its implications for hydroxide ion concentration.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant begins by writing the net ionic equation for the dissociation of Sr(OH)2, expressing uncertainty about how to proceed with the calculations.
  • Another participant suggests finding the concentration of OH- as a next step.
  • A participant references a textbook that indicates the concentration of OH- is 2 times the concentration of Sr(OH)2, questioning the reasoning behind using the moles of the solution.
  • Frustration is expressed by one participant regarding the lack of responses, questioning if their approach to asking the question is appropriate.
  • A response highlights the importance of understanding the definition of concentration and encourages considering the number of moles of Sr(OH)2 in a 1L solution to determine the moles of OH- produced.
  • Another participant reiterates the point about the number of moles of OH- in Sr(OH)2 and questions the rationale for multiplying the concentration by the number of moles in the reaction.
  • A question is posed about the definition of concentration, indicating a potential gap in understanding among participants.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the calculations and the reasoning behind them. There is no consensus on the best approach to solve the problem, and some participants appear to be struggling with foundational concepts.

Contextual Notes

Some participants may be missing foundational knowledge about concentration and dissociation, which affects their ability to engage with the problem effectively. The discussion reflects uncertainty about the application of stoichiometry in this context.

Who May Find This Useful

This discussion may be useful for students learning about acid-base chemistry, particularly those grappling with stoichiometric calculations and the dissociation of ionic compounds in solution.

IntegrateMe
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A solution is prepared to be 0.1475 M in Sr(OH)2. Find the [H3O+], [OH‐], pH, and pOH.

I'm not quite sure where to go from here. I was thinking I can start by writing out the net ionic equation:

Sr(OH)2 → Sr2+ + 2OH-

But I don't really know how that helps me. Any insights?
 
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Find the concentration of OH-.
 
The book shows that the concentration of OH is 2(.1475M), but I'm not sure how that was obtained. I understand that there are 2 hydroxide ions, but why do we use the moles of the solution?
 
Seriously, why can't ANYBODY help me? I figured the problem was relatively easy, am I asking in the wrong way?
 
Geez, you didn't get an answer in two hours, on the Independence Day evening, and you are already frustrated? Get some pills for patience.

Seeing how you don't know what to do makes me wonder you are missing... What is the definition of the concentration? If you have 1L of the 0.1475 M solution, how many of Sr(OH)2 are there? Look at the dissociation equation - how many moles of OH- are there?
 
Geez, you didn't get an answer in two hours, on the Independence Day evening, and you are already frustrated? Get some pills for patience.

Seeing how you don't know what to do makes me wonder you are missing... What is the definition of the concentration? If you have 1L of the 0.1475 M solution, how many moles of Sr(OH)2 are there? Look at the dissociation equation - how many moles of OH- are there?
 
There are 2 moles of OH- in Sr(OH)2.

Why do we multiple this 0.1475 M solution by the number of moles of one part of the reaction, though?
 
What is the definition of the concentration?
 

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