Lab13Questions ()ICompatibility Made)] Wd References Mailings Review ViewHelp Ge
ID: 592865 • Letter: L
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Lab13Questions ()ICompatibility Made)] Wd References Mailings Review ViewHelp General Lab Questions 1. In Activity I, what happened to the pH of the water sample as 0.1 M HCI was added? How did this compare to what happened with the addition of one drop of 0.1 M HCLto each buffer solution? 2. In Activity 1. why did the pH of the buffer solutions change after the addition of 10 drops of0.1 Mbare In Activity 2 which concentration was the effective buffer? Explain what happened chemicaly as the buffer became more cilute. 3. Explain how the buffer could be diluted (in Activity 2, yet maintain the same Hint: Reference the Henderson Hasselbalch e 4· 5. The pka of phosphoric acld is 7.21. What s the useful buffering range of this acid and its corjugate base? Briefy, explain. of the pH range determined in outside the cells? 6. If the pH of a Dlscussion Question 5, what wouid ho ipExplanation / Answer
Q1
a) addition of HCl to water --> decreases pH form neutral, p H= 7, to a very acidic value, ie.pH = 1-3 due to HCl acidity
b) when we add this to a buffer, the pH will not change drastically, mainly becausE:
A buffer is any type of substance that will resist pH change when H+ or OH- is added.
This is typically achieved with equilibrium equations. Both type of buffer will resist both type of additions.
When a weak acid and its conjugate base are added, they will form a buffer
The equations:
The Weak acid equilibrium:
HA(aq) <-> H+(aq) + A-(aq)
Weak acid = HA(aq)
Conjugate base = A-(aq)
Neutralization of H+ ions:
A-(aq) + H+(aq) <-> HA(aq); in this case, HA is formed, H+ is neutralized as well as A-, the conjugate
Neutralization of OH- ions:
HA(aq) + OH-(aq) <-> H2O(l) + A-(aq) ; in this case; A- is formed, OH- is neutralized as well as HA.
Now,
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