Skip to main content

If you added an equal volume of a strong alkali to a weak acid (e.g. vinegar pH=4) what pH would you expect to get?

The reaction of solutions of acid and base can be generally represented as:


Acid + Base = Salt + Water


where


Acid contains an H that can be protonated producing the conjugate base


and 


Base as an alkali base, has an alkali metal combined with a hydroxide.



In your question, the reaction of equal volume of vinegar with an alkali base can be represented as:



`CH_3 COOH + MOH = CH_3 COO^(-) M^(+) + H_2 O `


where


MOH is the Alkali base and;


CH3COOH is Acetic acid, the weak acid present in vinegars.


The concentration of the product CH3COO-M+ is dependent on the concentrations of the alkali base and the acid. 1 mole of the base reacting with 1 mole of the acid will produce 1 mole of CH3COO-M+ in the solution. The pH of the resulting solution will be greater than pH = 4 since the acetic acid will be consumed in the reaction. 


Since acetic acid is a weak acid, the neutralization reaction of 1 mole of the acid and 1 mole of the base will not give a neutral solution. The reason is because the salt CH3COO-M+ will dissociate in the same reaction as:



`CH_3 COO^(-) M^(+) = CH_3 COO^(-) + M^(+) `


where CH3COO- is the acetate ion and M+ is the alkali metal ion. 


The acetate ion being a conjugate base of a weak acid will react with the water in the solution as:



`CH_3 COO^(-) + H_2 O =CH_3 COOH + OH^(-). `


The production of OH- in the solution will increase the pH of the solution compared with the pH of vinegar.


Therefore, mixing equal volumes of alkali acid and acetic acid will increase the pH of the resulting solution. 

Comments

Post a Comment

Popular posts from this blog

Is there a word/phrase for "unperformant"?

As a software engineer, I need to sometimes describe a piece of code as something that lacks performance or was not written with performance in mind. Example: This kind of coding style leads to unmaintainable and unperformant code. Based on my Google searches, this isn't a real word. What is the correct way to describe this? EDIT My usage of "performance" here is in regard to speed and efficiency. For example, the better the performance of code the faster the application runs. My question and example target the negative definition, which is in reference to preventing inefficient coding practices. Answer This kind of coding style leads to unmaintainable and unperformant code. In my opinion, reads more easily as: This coding style leads to unmaintainable and poorly performing code. The key to well-written documentation and reports lies in ease of understanding. Adding poorly understood words such as performant decreases that ease. In addressing the use of such a poorly ...
Post a Comment
Read more

Is 'efficate' a word in English?

I routinely hear the word "efficate" being used. For example, "The most powerful way to efficate a change in the system is to participate." I do not find entries for this word in common English dictionaries, but I do not have an unabridged dictionary. I have checked the OED (I'm not sure if it is considered unabridged), and it has no entry for "efficate". It does have an entry for "efficiate", which is used in the same way. Wordnik has an entry for "efficate" with over 1800 hits, thus providing some evidence for the frequency of use. I personally like the word and find the meaning very clear and obvious when others use it. If it's not currently an "officially documented" word, perhaps its continued use will result in it being better documented.
Post a Comment
Read more