Can Hydroclauric Acid and Water Create a pH Greater than 7? Find Out Now!

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Discussion Overview

The discussion revolves around whether a solution of hydrochloric acid (HCl) and water can achieve a pH greater than 7. Participants explore theoretical scenarios, conditions, and the implications of dilution and temperature on pH levels.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • One participant questions if there are any situations where a solution of hydrochloric acid and water could have a pH greater than 7.
  • Another participant suggests that if the hydrochloric acid is very diluted and the water is not pure, it might be theoretically possible to achieve a pH greater than 7.
  • A third participant discusses the self-ionization of water and proposes that lowering the temperature could decrease the concentration of hydronium ions (H3O+), potentially resulting in a pH greater than 7 when very dilute HCl is added.
  • In contrast, another participant argues that hydrochloric acid inherently adds H+ ions, which lowers pH, but acknowledges that at temperatures below 25 degrees Celsius, pure water's pH can be slightly above 7, suggesting a scenario where a very dilute HCl solution might not lower the pH below 7.

Areas of Agreement / Disagreement

Participants express differing views on the possibility of achieving a pH greater than 7 with hydrochloric acid and water, with no consensus reached on the conditions under which this might occur.

Contextual Notes

Participants mention various conditions such as dilution, temperature, and the purity of water, which may affect the pH but do not resolve the underlying assumptions or dependencies related to these factors.

thee
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I want to ask that there is any situation that the solution of Hydroclauric acid and water can make the pH of this solution gretater than 7.
 
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Yes, to some extent. At pH 7 there is no abundance of H+ or OH-.

However, water has the following reaction:

H2O -> H+ + OH-

So strickly theoretically speaking, if the acid is very diluted, your water isn't pure and the conditions are favourable, why not?
 
2H_2O \longrightarrow H_3O^+ + OH^-

The self-ionization of water is endothermic (see reaction above). If you low the temperature, the concentration of H_3O^+ will diminish and the pH will be greater than 7 for a pure water. If you add very dilute hydrochloric acid at this conditions it is very probable that the pH of this solution is greater than 7.
 
Not really. HCl, Hydrochloric Acid can only ADD H+ ions, and LOWER the pH.
If you really want to nit pick, however...
At temperatures below 25 degrees C, the pH of pure water is slightly higher than 7.0. At 15 C, it's about 7.16, for example. So if you take cold water, and any such a tiny amount of HCL that it won't lower the pH below 7.0, you can have an HCL solution with a pH above 7.00. (But adding the HCl still lowered the pH a bit).
 

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