Which of the following aqueous solutions would test closet to pH 7

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Discussion Overview

The discussion revolves around identifying which of several aqueous solutions would test closest to pH 7. The solutions in question include sodium chloride (NaCl), sodium carbonate (Na2CO3), sodium dihydrogen phosphate (NaH2PO4), and sodium cyanide (NaCN). The context is homework-related, focusing on the concepts of acids, bases, and pH levels.

Discussion Character

  • Homework-related
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • One participant expresses confusion about why NaCl is considered to have a pH closest to 7, despite initially thinking that strong acids like HCl would lead to a low pH.
  • Another participant suggests considering relevant equations to understand the behavior of the solutions.
  • A reference to the Brønsted-Lowry definitions of acids and bases is made, indicating a potential avenue for clarification.
  • There is a suggestion to explore possible reactions of the listed substances using the Brønsted-Lowry definitions.
  • A participant questions the understanding of strong and weak acids, implying that this knowledge is crucial for the discussion.
  • Another participant introduces the concept of the dissociation constant, suggesting that it may provide insight into the acidity or basicity of the solutions.

Areas of Agreement / Disagreement

The discussion reflects a lack of consensus, with participants exploring different aspects of acid-base theory and the implications for the pH of the solutions. No definitive agreement on the reasoning behind the pH levels of the solutions has been reached.

Contextual Notes

Participants have not fully resolved the definitions and implications of strong versus weak acids, nor have they clarified the role of dissociation constants in determining pH levels. The discussion remains exploratory and focused on understanding the underlying concepts.

JessicaHelena
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Homework Statement


>Which of the following aqueous solutions would test closet to 7 on the pH scale?
$a) NaCl$, $b) Na_2CO_3$, $c) NaH_2PO_4$, $d) NaCN$

Homework Equations

The Attempt at a Solution


I don't understand this. So I tried writing chemical equations like for a), NaCl + H20 --> NaOH + HCl, and so on. But for example, HCl (the product in the previous equation) is a strong acid, so I thought it'd have a low pH, but apparently a) is actually the answer, and I don't know how to get that.
 
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Perhaps you need a relevant equation ? Any candidates ?
 
Do the names Brønsted-Lowry ring a bell?
 
@Borek — yes, kind of, it was about acids and bases definition, I think.
 
OK, so try to apply this definition and see what are possible reactions of the substances listed.
 
JessicaHelena said:
I don't understand this. So I tried writing chemical equations like for a), NaCl + H20 --> NaOH + HCl, and so on. But for example, HCl (the product in the previous equation) is a strong acid, so I thought it'd have a low pH, but apparently a) is actually the answer, and I don't know how to get that.

You are correct that HCl is a strong acid. Do you know what the definition of a strong acid is? Do you know what the definition of a weak acid is?
 
Do you understand the dissociation constant? Knowing this constant for the acids/bases can help you.
 

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