Questions & Answers

Question about acetate buffer and what happens when HCl is added to such a solution

Debra ask:How do I attack this problem?
I want to compare the effect of adding 1mmol of HCL to 100 ml of 0.2M acetate buffer at two different starting pH's.
(pKa of acetate buffer =4.7Initial pH = 4.7Initial pH = 5.7Thank you

Hi Debra,

There is both a short and long answer to your question. The short answer is that at pH=4.7 you are muchcloser to the equivalence point of your buffer (pH 4.7 when its a CH3COOHCH3COO- buffer) and at that pH the additionof HCl will cause a much larger change in pH than at pH=5.7.

However, you can calculate (this is the long answer) how much pH changes by doing some fairly simplecalculations. Since the explanation is not short I've made a separate webpage answering your question.It is named acetate buffer.The answer is also found as a pdf document named acetate buffer. The Excel spreadsheet showing allthe calculations is shownhere.


Question about glucose and ionic strength

Anonymous ask:what would be the ionic strenth of say 100mM Glucose? where there is no charge?

Dear Anonymous,

When there is no charge there is no contribution to the ionic strength. Ionic strength only counts charge ions.So, for any standard calculation glucose is not considered charged - and do not contribute to the overall ionicstrength of the solution. You can refer to the page about ionic strength.


An introduction to Ionic Strength BackgroundTo quantify the effect of inter-ionic interactions, such as molecular attraction and repelling, one has to have a `parameter` describing themagnitude of these forces and how they alter the way certain calculation are done.Topic: Equilibriums The pH s...

Buffers and Equilibriums As shortly explained in the section about how to calculate pH in a solution of dissolved NaHCO3, a buffer has the capability of keeping pH withina certain and narrow range even if an excess of hydrogen ions H+ or hydroxide ions OH- are added.In this particular page I will elaborate a bit on why buffers actually have the ca...

Acids and bases - Broensted-Lowry definition A more fundamental definition of acids and bases than the one provided on the index page was given by the Danish chemists Johannes Broensted.The definitions are:A Broensted acid is a proton doner.A Broensted base is a proton acceptor.The English chemist, Thomas Lowry, proposed exactly the same at roug...

PDF library Note: Discussions about the pdf documents are found in the 'Help & Discussions' section.Inorganic chemistry subjects:Equilibriums 1 : A tutorial about how [CO2], [HCO3-] and[CO32-] are calculated from Total Inorganic Carbon.The pdf is hereIonic Strength 1 : An introduction about Ionic Strength with a simple calculation using H+...