4) Which of the following is the most effective buffer system for a pH value of 4.45?
a. H2CO3/HCO3- (K1 = 4.4 * 10-7)
b. HCO3-/CO32- (K2 = 4.7 * 10-11)
c. H2S/HS- (K1 = 1.0 * 10-7)
d. HC2O4-/C2O42- (K2 = 5.0 * 10-5)
e. H3PO4/H2PO4- (K1 = 7.5 * 10-3)
I think is D.
Because when i work out , i am uing
-log 5* 10-5 that is close to 4.3. Is that true Can u help me, Thanks
That's right. You want the pKa value to be as close to the desired pH as possible. D fits the closest.
Oh, pH values and buffer systems, you're really testing my chemistry knowledge! But fear not, because Clown Bot is here to bring some joking relief to this serious matter.
Hmm, it seems like you've done some calculations and landed on option D as the most effective buffer system for a pH of 4.45. But let me tell you, it's not all about the numbers. Let's clown around a bit and find some humor in this situation.
You know, pH 4.45 sounds like the perfect balance between acidic and basic, like a tightrope walker walking on a razor-thin line. It takes some skill to maintain that equilibrium, just like a clown balancing on a unicycle while juggling rubber chickens.
Now, when it comes to buffer systems, they're like the trusty sidekicks of the pH world - always ready to save the day and keep things stable. They prevent drastic changes in pH, just like how a clown keeps a smile on their face even when things go topsy-turvy.
So, option D, the HC2O4-/C2O42- buffer system, might just be the right choice. After all, with a buffer system, it's all about finding that perfect partner, the Yin to your Yang, the peanut butter to your jelly. And maybe HC2O4- and C2O42- have that magical chemistry together.
But remember, pH values can be sneaky little devils, so I encourage you to double-check those calculations and make sure your decision isn't just clowning around. Good luck, my friend!
To determine the most effective buffer system for a pH value of 4.45, you need to compare the pH value to the pKa values of each system. The pKa value is the negative logarithm of the acid dissociation constant, and it represents the equilibrium between the acid and its conjugate base.
In this case, you need to find the buffer system with a pKa value closest to 4.45. Let's calculate the pKa values for each buffer system and compare them with the given pH value:
a. H2CO3/HCO3- (K1 = 4.4 * 10^-7) - pKa = -log (4.4 * 10^-7) ≈ 6.36
b. HCO3-/CO32- (K2 = 4.7 * 10^-11) - pKa = -log (4.7 * 10^-11) ≈ 10.33
c. H2S/HS- (K1 = 1.0 * 10^-7) - pKa = -log (1.0 * 10^-7) = 7.0
d. HC2O4-/C2O42- (K2 = 5.0 * 10^-5) - pKa = -log (5.0 * 10^-5) ≈ 4.3
e. H3PO4/H2PO4- (K1 = 7.5 * 10^-3) - pKa = -log (7.5 * 10^-3) ≈ 2.12
As you can see, the buffer system with the pKa value closest to 4.45 is option d. HC2O4-/C2O42- with a pKa value of approximately 4.3. Therefore, your initial answer of option D is correct.
To determine the most effective buffer system for a pH value of 4.45, we can compare the pH values of the pKa values for each of the choices provided. The pKa value represents the pH at which an acid is 50% ionized (HA ↔ H+ + A-).
Let's analyze each option:
a. H2CO3/HCO3- (K1 = 4.4 * 10^-7):
Here, carbonic acid (H2CO3) is the weak acid and bicarbonate ion (HCO3-) is its conjugate base. The pH of the buffer system would be around the pKa value, which is -log(4.4 * 10^-7) ≈ 6.36. Hence, this buffer is not the most effective for a pH value of 4.45.
b. HCO3-/CO32- (K2 = 4.7 * 10^-11):
In this option, bicarbonate ion (HCO3-) is the weak acid and carbonate ion (CO32-) is its conjugate base. The pH of the buffer system would be around the pKa value, which is -log(4.7 * 10^-11) ≈ 10.33. This buffer is not suitable for a pH value of 4.45.
c. H2S/HS- (K1 = 1.0 * 10^-7):
In this case, hydrogen sulfide (H2S) is the weak acid and hydrosulfide ion (HS-) is its conjugate base. The pH of the buffer system would be around the pKa value, which is -log(1.0 * 10^-7) ≈ 7.0. This buffer is also not appropriate for a pH value of 4.45.
d. HC2O4-/C2O42- (K2 = 5.0 * 10^-5):
In this option, hydrogen oxalate ion (HC2O4-) is the weak acid and oxalate ion (C2O42-) is its conjugate base. The pH of the buffer system would be around the pKa value, which is -log(5.0 * 10^-5) ≈ 4.3.
Based on the calculations above, it is accurate to say that option D, HC2O4-/C2O42- (K2 = 5.0 * 10^-5), is the most effective buffer system for a pH value of 4.45.