Answer:
The strong acid reacts with the weak base in the buffer to form a weak acid, which produces few H+ ions in solution and therefore only a little change in pH.
Explanation:
When a strong acid is added to the buffer, the acid dissociates and furnish hydrogen ions which combine with the conjugate of the weak acid, forming weak acid. The weak acid dissociates to only some extent and can furnish only some protons and there is no significant change in the pH.
Hence, option B is correct.
Answer:
pH = 1.32
Explanation:
H₂M + KOH ------------------------ HM⁻ + H₂O + K⁺
This problem involves a weak diprotic acid which we can solve by realizing they amount to buffer solutions. In the first deprotonation if all the acid is not consumed we will have an equilibrium of a wak acid and its weak conjugate base. Lets see:
So first calculate the moles reacted and produced:
n H₂M = 0.864 g/mol x 1 mol/ 116.072 g = 0.074 mol H₂M
54 mL x 1L / 1000 mL x 0. 0.276 moles/L = 0.015 mol KOH
it is clear that the maleic acid will not be completely consumed, hence treat it as an equilibrium problem of a buffer solution.
moles H₂M left = 0.074 - 0.015 = 0.059
moles HM⁻ produced = 0.015
Using the Henderson - Hasselbach equation to solve for pH:
ph = pKₐ + log ( HM⁻/ HA) = 1.92 + log ( 0.015 / 0.059) = 1.325
Notes: In the HH equation we used the moles of the species since the volume is the same and they will cancel out in the quotient.
For polyprotic acids the second or third deprotonation contribution to the pH when there is still unreacted acid ( Maleic in this case) unreacted.
No, they do not. Hope I helped! :)
Answer:
14.4 covers/hr.
Explanation:
First, we need to identify how much covers are produced in 1 hour, which will be total produced divided by the total time:
covers/hr = 120/10
covers/hr = 12
If the production will be increased by 20%, it means that new production will be the initial one plus 20% (0.20) of it:
12 + 0.20*12 = 14.4 covers/hr.
This problem is providing information about possible causes whereby mussel shells are being eroded due to the acidity in the ocean. In such a way, it claims that more acidic oceans dissolve calcium carbonate in a faster way and produce hydrogen carbonate ions, and thus, a feasible explanation is required as well as a hypothesis according to the following choices:
a. Lower CO₂; this reduces the H₂CO₃ and increases the pH.
b. Add CO₃²⁻: this will add base and increase its concentration.
c. Add Ca²⁺: this will increase the precipitation rate of calcium carbonate (correct choice).
<h3>Equilibrium equations:</h3>
At first instance, we should recall the equilibrium equations that take place when acidic oceans dissolve calcium carbonate in a faster way:
<h3>Shifts from equilibrium:</h3>
Where we can see that the first choice is thoroughly discarded as the addition of CO₂ actually increases the ionizable carbonic acid (acidity). Moreover, the addition of CO₃²⁻ may also lead to the formation of more protons-releasing carbonic acid which also contributes to the acidity of the ocean.
<h3>Hypothesis:</h3>
Thereby, the correct condition that, for sure, contributes to the preservation of mussel shells will be the addition of Ca²⁺ and the hypothesis will be that it shifts the equilibrium towards the formation of more CaCO₃, the active compound in these shells.
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