Hi can someone please help me with this. Thank you!!

Question

calculate the concentration of the hydrogen ion/hydroxide ion in

the samples below by its pOH level. Identify if the solution is acidic, basic, or neutral.

1. Calculate the hydroxide

ion concentration of a

solution with a pOH

level of 3.80.

2. Calculate the hydroxide

ion concentration if a

solution has a pOH

reading of 12.24.

3.Calculate the

hydroxide ion

concentration of a

solution with a pH

reading of 14.

Answer 1

Hello, Shin,

pOH and pH are the negative logs of the OH and H concentrations. So a pOH of 3.8 would mean that the concentration of OH is

[OH^-] = 1x10^-3.8 M

At STP, pure water is in equilibrium with it's component ions:

H₂O = H⁺ + OH^-

The equilibrium coefficient for this is 1x10^-14. So we can write

1x10^-14 =[H⁺]*[OH^-]

Now we can find [H⁺]

1x10^-14 =[H⁺]*[1x10^-3.8]

[H⁺] = [1x10^-3.8]/[1x10^-14]

[H⁺] = [1x10^+10.2]

The negative log of this number is 10.2

pH = 10.2

The above calculation is the fundamental relationship between pH and pOH of water. Once this is understood, it makes sense to use a much quicker approach. pH and pOH must always sum to 14 for water. If pOH is 3.8, then pH is 14 - 3.8, or 10.2.

2. pOH = 12.36. Use the definition of pOH: The negative log of the hydroxide ion concentration. That means [OH^-] = 10^-12.36. That is the same as 4.37x10^-13

3. pH = 14. Repeat the above steps. [H⁺] = 10^-14

[10^-14]*[OH^-] = 10^-14

[OH^-] = 1

Bob