Answer:
Ka= 3.37×[tex]10^{-9}[/tex]
Explanation:
Ka is the measure of an acid's ability to donate H+ ions. A strong acid will have a larger Ka value. Consider the following equation
HA + H2O → H3O+ + A-
where,
HA is acid, which when dissolves in a solution dissociates into hydronium ion and A- ion. Ka will be represented as
Ka = [tex]\frac{[H+] [A-]}{[HA]}[/tex]
Step 1
calculate the number of moles of thiamine hydrochloride
no of moles(n)=g/MM
n=1.00/337.3
n=2.96×[tex]10^{-3}[/tex]
Step 2
The solution was diluted to 10.00ml
∵ 2.96×[tex]10^{-3}[/tex]/ 0.01 L
=0.296M
Step 3
Find H+ using the formula
pH= -log [H+}
4.50= -log [H+]
[H]= [tex]10^{-4.50}[/tex]
[H]=3.16×[tex]10^{-5}[/tex]
Step 4
Substitude the above values in the formula
Ka=[tex]\frac{[H+] [A-]}{[HA]}[/tex]
=[tex]\frac{[0.0000316] [0.000316]}{0.296}[/tex]
= 3.37×[tex]10^{-9}[/tex]
