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NorthRokas

I need help for chemistry/biochemistry

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for my science project I’m testing pepsin, so I need somehow get HCl = 2pH. I know there is way from concentration calculate pH, but I don’t know how. Maybe someone  can send me some examples, how to calculate that or explaine or send the link with explanation.

Also maybe someone can send me conspects or articles abouot pepsin and digestion, proteins

appreciate any help.

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Posted (edited)
1 hour ago, NorthRokas said:

for my science project I’m testing pepsin, so I need somehow get HCl = 2pH. I know there is way from concentration calculate pH, but I don’t know how. Maybe someone  can send me some examples, how to calculate that or explaine or send the link with explanation.

Also maybe someone can send me conspects or articles abouot pepsin and digestion, proteins

appreciate any help.

So let us start with the basics.

Do you understand what a pH of 2 means?

Do you understand the difference between a strong acid and a weak acid?

Which do you think hydrochloric acid is?

Edited by studiot

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13 minutes ago, studiot said:

So let us start with the basics.

Do you understand what a pH of 2 means?

Do you understand the difference between a strong acid and a weak acid?

Which do you think hydrochloric acid is?

I know that pH stands for 'potential of Hydrogen.

 Strong acids have a higher concentration of hydrogen ions than weak acids.

 strong acid

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Posted (edited)

Yes HCl is officially a strong acid which means that it is fully dissociated at the concentrations to produce a pH of 2.

pH is defined as the logarithm of the reciprocal hydrogen ion concentration.

This also equals the negative of the log log the hydrogen ion concentration

pH = -log[H+]

(Some people like to use the hydroxinium ion H3O+, but I see little point for this purpose)

So you need the hydrogen ion concetration, in moles per litre.

Can you have a stab at it now?

What is the dissociation reaction?

 

Here is a tip if you are plotting something against pH in you experiment.

pH   conc of HCl to achieve that pH in M/litre

1            0.1
2            0.01
3            0.001
4            0.0001
5             0.00001

This is very easy.
It is more complicated if you use a weak acid such as acetic, which often happens in biochemistry.

Edited by studiot
spelling

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On 10/8/2019 at 1:23 PM, BabcockHall said:

What do you know about pepsin, and what do you hope to learn?

I  need few pages of information and operating conditions, if you have or know some articles or books, it would be perfect if you send me a link.

My knowledge about pepsin pretty basic.

Sorry for late respond.

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There is a little bit of information on page 92 of Biochemica Information, by Joseph Keesey.  He notes that it can catalyze transpeptidations and that the pH optimum  is between 2-4.  Offhand, I do not know of a good source, but the BRENDA compendium of information might be worth checking out.

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