What is the mass of an atom that has 4 protons, 5 neutrons, and 4 electrons?
2 answers:
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Answer:
pH of buffer after addition of 1 mL of 0,1 M HCl = 7,0
Explanation:
It is possible to use Henderson–Hasselbalch equation to estimate pH in a buffer solution:
pH = pka + log₁₀
Where A⁻ is conjugate base and HA is conjugate acid
The equilibrium of phosphate buffer is:
H₂PO₄⁻ ⇄ HPO4²⁻ + H⁺ Kₐ₂ = 6,20x10⁻⁸; pka=7,2
Thus, Henderson–Hasselbalch equation for 7,00 phosphate buffer is:
7,0 = 7,2 + log₁₀
Ratio obtained is:
0,63 =
As the problem said you can assume [H₂PO₄⁻] = 0,1 M and [HPO4²⁻] = 0,063M
As the amount added of HCl is 0,001 M the concentrations in equilibrium are:
H₂PO₄⁻ ⇄ HPO4²⁻ + H⁺
0,1 M +x 0,063M -x 0,001M -x -<em>because the addition of H⁺ displaces the equilibrium to the left-</em>
Knowing the equation of equilibrium is:
Replacing:
6,20x10⁻⁸ =
You will obtain:
x² -0,064 x + 6,29938x10⁻⁵ = 0
Thus:
x = 0,063 → No physical sense
x = 0,00099990
Thus, [H⁺] in equilibrium is:
0,001 M - 0,00099990 = 1x10⁻⁷
Thus, pH of buffer after addition of 1 mL of 0,1 M HCl =
-log₁₀ [1x10⁻⁷] = 7,0
A buffer is a solution that can resist pH change upon the addition of an acidic or basic components. In this example you can see its effect!
I hope it helps!
Explanation:
The pH of a substance can be found by using the formula
where [ H+ ] is the hydrogen ion concentration in the substance
From the question
[ H+ ] = 2.1 × 10-¹² M
To find the pH substitute the value into the above formula
We have
We have the answer as
<h2>pH = 11.7 </h2>The solution is basic since it lies in the basic region that is from 8 to 14
Hope this helps you