Henderson Hassalbach equation problem

  • Thread starter Thread starter hianghao
  • Start date Start date
AI Thread Summary
To prepare a 1L Tris-HCl buffer at pH 7 with a pKa of 8.06, the necessary calculations indicate that 0.08M of the base (Tris) and 0.92M of HCl are required. The reaction involves the neutralization of HCl, resulting in the formation of Tris hydrochloride without producing water as a product. The discussion emphasizes the importance of understanding the relationship between acids and their conjugate bases in buffer solutions. It also clarifies that HCl acts as the acid in this context, donating protons to establish the desired pH. Overall, the focus is on achieving the correct molar concentrations for effective buffer preparation.
hianghao
Messages
5
Reaction score
0

Homework Statement


I am trying to prepare a 1L Tris-HCl buffer 1M pH7. The pKa value is 8.06. The question is, how many molar of HCl should be added to produce this buffer?


Homework Equations


pH = pKa + log [base/acid]


The Attempt at a Solution


7=8.06 + lg (a/b)
-1.06=lg (a/b)
a/b = 0.0871 -----1
a+b= 1M
a=1-b --------2
Hence,
(1-b)/b = 0.0871
b = 0.92M
a = 0.08M
So, the molarity of HCl to be added is 0.92M or 0.08M. Why?
 
Physics news on Phys.org
What reaction takes place when you add HCl?

--
 
hianghao said:
C4H11NO3 + HCl <-> C4H10NO2Cl + H2O?

No. HCl is neutralized, but there is no water between products. TRIS hydrochloride is produced.

Because b=salts conc while a=acid/base conc?

Buffer is a mixture of salt & acid/base, but acid and conjugate base.

You need to identify an acid and its conjugate base in the case of TRIS.

What is a Broensted acid? What is a Broensted base? How are they related?

--
methods
 
Borek said:
No. HCl is neutralized, but there is no water between products. TRIS hydrochloride is produced.
Buffer is a mixture of salt & acid/base, but acid and conjugate base.

You need to identify an acid and its conjugate base in the case of TRIS.

What is a Broensted acid? What is a Broensted base? How are they related?

--
chemical calculators - buffer calculator, concentration calculator
www.titrations.info - all about titration methods


So buffer should be acid+conjugate base or base + conjugate acid.
Bronsted Acid donate proton while base receive proton.
HCl is suppose to be the acid because it has H+ to be donated.

If no water product, could it be
(CH2OH)3CNH2 + HCl <> (CH2OH)3CCl + NH3?
but still it doesn't become TRIS hydrochloride..
Or it becomes (CH2OH)2CClNH2+ CH3OH? I can't hink of other possiblity..
 
Last edited:
Thread 'Confusion regarding a chemical kinetics problem'

Thread 'Confusion regarding a chemical kinetics problem'

TL;DR Summary: cannot find out error in solution proposed. [![question with rate laws][1]][1] Now the rate law for the reaction (i.e reaction rate) can be written as: $$ R= k[N_2O_5] $$ my main question is, WHAT is this reaction equal to? what I mean here is, whether $$k[N_2O_5]= -d[N_2O_5]/dt$$ or is it $$k[N_2O_5]= -1/2 \frac{d}{dt} [N_2O_5] $$ ? The latter seems to be more apt, as the reaction rate must be -1/2 (disappearance rate of N2O5), which adheres to the stoichiometry of the...
View full post »

Similar threads

Determining pH using Henderson-Hasselbach equation?
Replies
12
Views
2K
Henderson Hasselbalch Buffers and Volumes
Replies
1
Views
3K
I need some help in this question please check what i have done
Replies
5
Views
2K
Chemistry Comparing methods of computing pH at equivalence point in titration
Replies
4
Views
1K
Best optimal buffer, highest buffering capacity against naoh
Replies
7
Views
6K
How Does Pre-existing CH3COONa Affect Buffer pH Calculation?
Replies
4
Views
2K
Chemistry Moles of a conjugate base in a buffer solution
Replies
7
Views
3K
Chemistry Moles of NaOH to Create Buffer Solution pH=6 in 0.42M Ethanoic Acid
Replies
3
Views
3K
Henderson-Hasselbalch buffer calculations - B + A Question
Replies
8
Views
3K
Volumes of a Buffer using Henderson-Hasselbalch?
Replies
1
Views
4K

Hot Threads

Recent Insights

Back
Top