# chemistry

posted by .

What mass in grams of potassium hydroxide is cntained in 500 mL of solution that has a pH of 11.5?

chemistry - DrBob222, Sunday, April 6, 2008 at 12:09am
pH = 11.5
pOH = 14 - 11.5 = 2.5
pOH = -log(OH^-) ] 2.5
(OH^-) = ??
KOH ==> K^+ + OH^-
This is a strong base.
You have the (OH^-) which is mols/L. Take 1/2 that to find the mols in 500 mL, Then grams = mols x molar mass. Post your work if you get stuck

[OH] = 1.0 x 0^-14 / 11.5

= 8.69 x 10^-16 / 2

= 4.34 x 10^-16

g = 4.34 x 10^-16 x 56.10564 g/mol

= 2.4 x 10^-15

I got a wrong answer what ma I doing that's incorrect?

• chemistry -

pH = 11.5
pOH = 14 - 11.5 = 2.5
pOH = -log(OH^-) ] 2.5
(OH^-) = ??
KOH ==> K^+ + OH^-
This is a strong base.
You have the (OH^-) which is mols/L. Take 1/2 that to find the mols in 500 mL, Then grams = mols x molar mass. Post your work if you get stuck

[OH] = 1.0 x 0^-14 / 11.5 This isn't correct. If the pH is 11.5, then the pOH = 14 - 11.5 = 2.5 = pOH and (OH^-) = 0.00316 M. It appears to me that you have Kw mixed up with pKw.

= 8.69 x 10^-16 / 2

= 4.34 x 10^-16

g = 4.34 x 10^-16 x 56.10564 g/mol

= 2.4 x 10^-15

## Similar Questions

1. ### Repost for Dora

solution is made by mixing 20.0 mL of toluene C6H5CH3d=0.867gmL with 150.0 mL of benzene C6H6d=0.874gmL. Assuming that the volumes add upon mixing, what are the molarity (M) and molality (m) of the toluene For Further Reading * chemistry …
2. ### chemistry

What mass in grams of potassium hydroxide is cntained in 500 mL of solution that has a pH of 11.5?
3. ### chemistry

What mass in grams of potassium hydroxide is contained in 500 mL of solution that has a pH of 11.5?
4. ### Chemistry

A student makes a solution by dissolving 55.8 grams of potassium hydroxide in 875.0 grams of water. The resulting solution has a density of 1.07 grams per milliliter. 1. What is the volume of this solution?
5. ### Chemistry

A student makes a solution by dissolving 55.8 grams of potassium hydroxide in 875.0 grams of water. The resulting solution has a density of 1.07 grams per milliliter. 1. What is the volume of this solution?
6. ### Chemistry

A student makes a solution by dissolving 55.8 grams of potassium hydroxide in 875.0 grams of water. The resulting solution has a density of 1.07 grams per milliliter. 1. What is the volume of this solution?
7. ### Chemistry

A student makes a solution by dissolving 55.8 grams of potassium hydroxide in 875.0 grams of water. The resulting solution has a density of 1.07 grams per milliliter. 1. What is the volume of this solution?
8. ### Chemistry- Drbob-help

I have placed the answer I got please help. A student makes a solution by dissolving 55.8 grams of potassium hydroxide in 875.0 grams of water. The resulting solution has a density of 1.07 grams per milliliter. 1. What is the volume …
9. ### Chemistry- Drbob-help#3

I still need help with #3 I'm not sure how I got 1.14M. I have tried to do the problem over, but I not coming up with my original answer of 1.14M. Somehow I am missing a step. Please show work for the 1.14M Thanks Question#9 reads …