Equilibrium of NH4F, (NH4)2S, and MgO in Water: Reactants or Products?

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Discussion Overview

The discussion revolves around the equilibria of various substances when introduced into water, specifically focusing on NH4F, (NH4)2S, and MgO. Participants explore whether the resulting equilibria favor products or reactants, engaging in a mix of theoretical reasoning and practical application related to hydrolysis and acid-base reactions.

Discussion Character

  • Homework-related
  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that determining whether products or reactants are favored requires a Keq calculation, asserting that Keq > 1 indicates products and Keq < 1 indicates reactants.
  • Another participant corrects the initial equilibrium equation for NH4F, stating that ionic salts dissociate completely in aqueous solutions and proposes hydrolysis equations for the ions NH4+ and F-.
  • There is a discussion about the hydrolysis of both ions, with one participant questioning the inclusion of water in the equilibrium expressions.
  • Multiple participants express confusion regarding the calculations and methodologies for determining Keq for various substances, particularly MgO and its interactions with water.
  • One participant raises a concern about identifying acids and bases in the context of HS- and NO2-, leading to further exploration of their roles in equilibrium reactions.
  • Another participant emphasizes the importance of including water in the equilibrium equations, suggesting that it acts as an acid in certain reactions.

Areas of Agreement / Disagreement

Participants exhibit a mix of agreement and disagreement, particularly regarding the correct formulation of equilibrium equations and the role of water in these reactions. Some participants propose different methods for calculating Keq, leading to unresolved questions about the accuracy of their approaches.

Contextual Notes

Participants express uncertainty about the assumptions underlying their calculations, particularly concerning the behavior of weak acids and bases in solution. There are unresolved mathematical steps and differing interpretations of how to approach the hydrolysis of the substances discussed.

Who May Find This Useful

This discussion may be useful for students studying chemical equilibria, particularly in the context of acid-base reactions and hydrolysis in aqueous solutions.

  • #31
Why would they give me such a question that doesn't fit with the method they want me to use ? and that question seems fishy to me because there is no product acid only the reactant acid (water) unless they assumed something that makes the answer turn out to be inequality. And that assumption they think I should know which I really really really really don't know. I've tried and tried until my personality split and still cannot figure out how they came up with answer like that.

if there is anyone else on this forum that knows why the answer is an inequality then please help me with it. Your help is greatly appreciated but I am still not going to leave this question alone. And one thing I still can't figure out is how did they come up with answer as large as to the magnitude of 22 !

Nothing makes sense to me with that question.
 
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  • #32
As mentioned before, this question is more than just acid-base equlibria. Take into account that Mg(OH)2 has a low Ksp as well, so consider its solubility equilibria.

I'm not sure how they got that number, but you can imagine that it'll be huge. Any OH- produced will precipitate out, lowering OH- concentration and driving the reaction forward to a virtual completion.
 
  • #33
Do I just leave that question then?
 
  • #34
Has anyone come across a question like this?
 

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