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Topic: Finding the pH of NaCl dissolved in water  (Read 2157 times)

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Offline Buddy_123

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Finding the pH of NaCl dissolved in water
« on: February 12, 2021, 08:09:03 PM »
Is there a way to use the ice table to find the pH of 0.1 NaCl?

I know that the strong acid (HCl) and strong base (NaOH) means that it is neutral so the pH is 7. But I'm not sure how I'd show that using the Ice table.
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Offline jeffmoonchop

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Re: Finding the pH of NaCl dissolved in water
« Reply #1 on: February 12, 2021, 10:47:02 PM »
The pH of a salt solution is low, 5
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Offline AWK

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Re: Finding the pH of NaCl dissolved in water
« Reply #2 on: February 13, 2021, 01:41:51 AM »
The pH correction related to the ionic strength of the solution is outside the ICE table. For a 0.1 M NaCl solution, this correction will be negligible. Read an advanced physical chemistry textbook.
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Offline AWK

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Re: Finding the pH of NaCl dissolved in water
« Reply #3 on: February 13, 2021, 03:03:11 AM »
Quote from: jeffmoonchop on February 12, 2021, 10:47:02 PM
The pH of a salt solution is low, 5
Show your calculations.
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Offline jeffmoonchop

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Re: Finding the pH of NaCl dissolved in water
« Reply #4 on: February 16, 2021, 11:57:19 AM »
Quote from: AWK on February 13, 2021, 03:03:11 AM
Quote from: jeffmoonchop on February 12, 2021, 10:47:02 PM
The pH of a salt solution is low, 5
Show your calculations.

Dissolve salt in water, measure pH.
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Offline DrCMS

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Re: Finding the pH of NaCl dissolved in water
« Reply #5 on: February 17, 2021, 08:38:54 AM »
Quote from: jeffmoonchop on February 16, 2021, 11:57:19 AM
Quote from: AWK on February 13, 2021, 03:03:11 AM
Quote from: jeffmoonchop on February 12, 2021, 10:47:02 PM
The pH of a salt solution is low, 5
Show your calculations.

Dissolve salt in water, measure pH.

Did that just now and I got pH ~6.5
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Offline shchavel

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Re: Finding the pH of NaCl dissolved in water
« Reply #6 on: February 25, 2021, 09:58:13 AM »
Quote from: DrCMS on February 17, 2021, 08:38:54 AM
Quote from: jeffmoonchop on February 16, 2021, 11:57:19 AM
Quote from: AWK on February 13, 2021, 03:03:11 AM
Quote from: jeffmoonchop on February 12, 2021, 10:47:02 PM
The pH of a salt solution is low, 5
Show your calculations.

Dissolve salt in water, measure pH.

Did that just now and I got pH ~6.5

Because it depends on water more than on salt)
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Offline DrCMS

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Re: Finding the pH of NaCl dissolved in water
« Reply #7 on: February 25, 2021, 11:36:52 AM »
Quote from: shchavel on February 25, 2021, 09:58:13 AM
Quote from: DrCMS on February 17, 2021, 08:38:54 AM
Quote from: jeffmoonchop on February 16, 2021, 11:57:19 AM
Quote from: AWK on February 13, 2021, 03:03:11 AM
Quote from: jeffmoonchop on February 12, 2021, 10:47:02 PM
The pH of a salt solution is low, 5
Show your calculations.

Dissolve salt in water, measure pH.

Did that just now and I got pH ~6.5

Because it depends on water more than on salt)

The water I used was distilled and had a measured pH, on a recently calibrated pH meter, of ~7.1 before I added the salt and ~6.5 afterwards.
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Offline jeffmoonchop

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Re: Finding the pH of NaCl dissolved in water
« Reply #8 on: February 25, 2021, 11:58:23 AM »
Maybe I was exaggerating a little when I said 5, but on the whole salt reduces pH. Could be to do with additional absorption of CO2 from the atmosphere. The saline solution we use measures 5.5. How much salt did you add?
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Offline DrCMS

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Re: Finding the pH of NaCl dissolved in water
« Reply #9 on: February 25, 2021, 12:09:06 PM »
Quote from: jeffmoonchop on February 25, 2021, 11:58:23 AM
How much salt did you add?

Enough to make 0.1M NaCl
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Offline Vidya

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Re: Finding the pH of NaCl dissolved in water
« Reply #10 on: March 01, 2021, 01:27:03 AM »
May be due to some impurity in the salt.
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Offline DrCMS

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Re: Finding the pH of NaCl dissolved in water
« Reply #11 on: March 01, 2021, 11:49:27 AM »
Quote from: Vidya on March 01, 2021, 01:27:03 AM
May be due to some impurity in the salt.

It was >99% NaCl sold by a reputable chemical lab supplier.
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