October 17, 2021, 08:12:06 PM
Forum Rules: Read This Before Posting


Topic: How strongly affected is the buffering capacity of sodium carbonate - sodium bic  (Read 171 times)

0 Members and 1 Guest are viewing this topic.

Offline naman1008

  • New Member
  • **
  • Posts: 4
  • Mole Snacks: +0/-0
I would like to do a lab regarding the affects of temperature on the buffering capacity of sodium carbonate - sodium bicarbonate in particular for sulfuric acid. Currently I have two competing theories,

a) according the la chatliers principle the increasing heat should increase the reactivity of the acid thus reducing the effective buffering capacity,

b) according to Van 't Hoff equation the acid dissociation constant should be reduced, increasing the effective buffering capacity.

can anyone offer further insight or resources regarding this, theoretical or experimental?

A lot of my information especially point B came from this post What's the effect of temperature on buffering capacity? similarly this post provided me a direction for inquiry regarding point A https://www.reddit.com/r/chemhelp/comments/9mqlcq/how_does_increasing_temperature_affect_the_buffer/
« Last Edit: October 12, 2021, 07:46:39 PM by naman1008 »

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 26791
  • Mole Snacks: +1737/-403
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
How do you define buffering capacity?

Definition I know and use is based on Ka so the buffering capacity is a function of initial pH and Ka.

https://www.chembuddy.com/?left=pH-calculation&right=pH-buffer-capacity

According to this definition buffering capacity doesn't get reduced/increased, just the position of maximum capacity shifts depending on the value of the [itex]\frac{dpK_a}{dT}[/itex].
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info

Offline naman1008

  • New Member
  • **
  • Posts: 4
  • Mole Snacks: +0/-0
This is how I'm defining buffer capacity, β = n / ΔpH, however based on Le Chatelier's principle and the Van 't Hoff equation the acid strength is proportional to the temperature. Based on this the base would be able to neutralize less acid and thus the buffer capacity should be reduced. I think.

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 26791
  • Mole Snacks: +1737/-403
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
You are confusing things. "Acid/base strength" is its willingness to dissociate, not its ability to neutralize. The neutralization stoichiometry doesn't change with the temperature.
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info

Sponsored Links