Hi! I am very stuck with these problems. I have tried to solve for each of these values, but I keep getting the answers wrong.
Q:
For each of the following strong base solutions determine OH-, H3O+, pH, and pOH:
8.66×10−3 M LiOH
1.15×10−2 M Ba(OH)2
2.2×10−4 M KOH
4.9×10−4 M Ca(OH)2
Hi! I'd be happy to help you with these problems. To find the values for OH-, H3O+, pH, and pOH for each of the given strong base solutions, we need to use some concepts from chemistry.
First, let's understand a few important concepts:
1. Strong Bases: Strong bases are substances that completely dissociate in water, forming hydroxide ions (OH-). Examples of strong bases include LiOH, Ba(OH)2, KOH, and Ca(OH)2.
2. Dissociation of Strong Bases: When a strong base dissociates in water, it releases hydroxide ions (OH-) but does not generate any hydronium ions (H3O+).
Now let's calculate the values for each given strong base solution:
1. 8.66×10−3 M LiOH:
Since LiOH is a strong base, it fully dissociates in water, so the concentration of OH- is equal to the concentration of LiOH: 8.66×10−3 M.
Since LiOH does not produce any hydronium ions, the concentration of H3O+ is 0.
To find pH, we can use the formula: pH = -log[H3O+]. Since the concentration of H3O+ is 0, the pH is not defined.
pOH is calculated using the formula: pOH = -log[OH-]. So, pOH = -log(8.66×10−3) = 2.06.
2. 1.15×10−2 M Ba(OH)2:
Similar to LiOH, Ba(OH)2 is also a strong base that fully dissociates in water. Therefore, the concentration of OH- is equal to the concentration of Ba(OH)2: 1.15×10−2 M.
Since Ba(OH)2 does not produce any H3O+ ions, the concentration of H3O+ is 0.
pH is not defined since the concentration of H3O+ is 0.
pOH is calculated using the formula: pOH = -log[OH-]. So, pOH = -log(1.15×10−2) = 1.94.
3. 2.2×10−4 M KOH:
Again, KOH is a strong base, and it fully dissociates in water. Thus, the concentration of OH- is equal to the concentration of KOH: 2.2×10−4 M.
Since KOH does not produce any H3O+ ions, the concentration of H3O+ is 0.
pH is not defined due to the concentration of H3O+ being 0.
pOH is calculated using the formula: pOH = -log[OH-]. So, pOH = -log(2.2×10−4) = 3.66.
4. 4.9×10−4 M Ca(OH)2:
Similar to the previous cases, Ca(OH)2 is a strong base, and it completely dissociates in water. Hence, the concentration of OH- is equal to the concentration of Ca(OH)2: 4.9×10−4 M.
Since Ca(OH)2 does not produce any H3O+ ions, the concentration of H3O+ is 0.
pH is not defined as the concentration of H3O+ is 0.
pOH is calculated using the formula: pOH = -log[OH-]. So, pOH = -log(4.9×10−4) = 3.31.
I hope this explanation helps you understand how to calculate the values for each of these strong base solutions. If you have any further questions, feel free to ask!