Neutralizing a basic reaction with HCl

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    Hcl Reaction
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Discussion Overview

The discussion revolves around the neutralization of a basic solution formed by reacting methyl salicylate with sodium hydroxide, specifically focusing on the appropriate amount of hydrochloric acid (HCl) needed for neutralization. The scope includes stoichiometric calculations and considerations for the reaction procedure in a laboratory setting.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant asks whether the amount of HCl needed for neutralization should consider the presence of methyl salicylate or be based solely on the amount of sodium hydroxide added.
  • Another participant suggests adding HCl drop-wise until a neutral pH is achieved, indicating a practical approach to the problem.
  • A participant emphasizes the need for prior calculation of HCl before coming to the lab, indicating a preference for a more precise method.
  • One participant points out the importance of considering the reactions and substances present when adding acid, highlighting the role of stoichiometry and the potential need to protonate salicylic acid.
  • A participant confirms that if 120 mmoles of NaOH are present, then 120 mmoles of HCl would be required for neutralization, conditional on the initial amount of NaOH.
  • Another participant questions whether the scenario is similar to starting with a saline solution and suggests that only a few drops of acid or alkali might be needed to adjust the pH.
  • A later reply warns that the pH may not be raised sufficiently with just a few drops and advises writing out the reaction equation for clarity.

Areas of Agreement / Disagreement

Participants express differing views on the method of determining the amount of HCl needed, with some advocating for calculations based on stoichiometry while others suggest a more experimental approach. The discussion does not reach a consensus on the best method for neutralization.

Contextual Notes

Participants note the importance of considering the specific reactions and substances involved, as well as the potential implications of whether the goal is merely neutralization or also protonation of salicylic acid. There is an acknowledgment of the need for precise calculations, but also a recognition of practical laboratory techniques.

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Homework Statement


I am reacting methyl salicylate with sodium hydroxide to produce salicylic acid. However, first it is important to add acid to neutralize the very basic solution.

My question is, when determining the amount of HCl to add, do I need to take into consideration the methyl salicylate? Or am I just basing it off of the amount of sodium hydroxide I add?


Homework Equations





The Attempt at a Solution

 
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Can you simply add the HCl drop-wise until your pH probe or paper yields a neutral result?
 
No, I am supposed to calculate the number before coming to lab.
 
Think what reactions take place and what substances are present in the mix when you start adding acid. This is just a simple stoichiometry.

The only tricky part is whether you want to just neutralize, or to acidify to protonate salicylic acid. That depends on the procedure you are going to follow.
 
So if I am just trying to neutralize, and if I have 120 mmoles of NaOH, then I would need 120 mmoles of HCl to neutralize, right?
 
IFF you have 120 mmoles of NaOH - yes.
 
Is this any different to just starting with a saline solution? Perhaps with 2 or 3 drops of acid or alkali added to tilt the pH one way or the other?
 
First, you won't get pH high enough. Second, write reaction equation.
 

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