I ONLY NEED HELP WITH PART A NOW PLEASE. THANKS SO MUCH :) Part A What is the H+

Question

I ONLY NEED HELP WITH PART A NOW PLEASE. THANKS SO MUCH :)

Part A

What is the H+ concentration for an aqueous solution with pOH = 4.37 at 25 ?C?

Express your answer to two significant figures and include the appropriate units.

Part B

Arrange the following aqueous solutions, all at 25 ?C, in order of decreasing acidity.

Rank from most acidic to most basic. To rank items as equivalent, overlap them.

1. pH=5.45

2. 0.0018 M KOH

3. 0.0023 M HCl

4. pOH=8.55

Part C

At a certain temperature, the pH of a neutral solution is 7.72. What is the value of Kw at that temperature?

Express your answer numerically using two significant figures.

Explanation / Answer

Part - A

Since pH + pOH = 14.000 at 25C, then ...
pH = 14.000 - pOH
pH = 14.000 - 4.370 = 9.63
[H+] = 10^-pH = 10^-9.63 = 2.344x10^-10 mol/L

Part - B

0.0023 M HCl => 0.0023 M of H+ => pH = -log(0.0023) = 2.64
pOH = 8.55 => pH = 5.45
pH = 5.45
0.0018 M KOH => 0.0018 M of OH- => pOH = -log[OH] = 2.74 => pH = 11.25
=> Rank from most acidic to most basic:
0.0023 M HCl > pOH = 8.55 = pH = 5.45 > 0.0018 M KOH
I think the only thing that makes the answer is wrong is because you rank pH = 5.45 > pOH = 8.55 while they are actually equal!

Part - C

ph=-log[H+]
7.72=-log[H+]
[H+]=1.905*10^-8

Since it is a neutral solution [H+]=[OH-],
Kw=[H+][OH-]
Kw=(1.905*10^-8)^2
Kw=3.629* 10 ^-16

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