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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Nat360 on November 15, 2021, 08:15:58 PM

Title: Increasing water pH level
Post by: Nat360 on November 15, 2021, 08:15:58 PM
Hi everyone.

I am doing an assignment which requires me to change the pH level of water and complete testing on it. I know that pH is dependent on the H+ ions in a solution, so how would I increase the H+ ions in water?

I was planning on dissolving a acid in water, but I am unsure of how to seperate the water from the acid while still maintaining the pH level.

Thanks for all your help in advance.
Title: Re: Increasing water pH level
Post by: Borek on November 16, 2021, 02:55:22 AM
I was planning on dissolving a acid in water

Dissolving a solid acid, or adding acid solution. Yes, that's the correct way of decreasing pH.

Quote
but I am unsure of how to seperate the water from the acid while still maintaining the pH level.

Why do you want to separate them? Please elaborate, as I fell you are misunderstanding something here.

Also note: if you want good control of pH it is better to not just add acid/base, but to use buffers. That's how the research in different pHs is typically carried out.
Title: Re: Increasing water pH level
Post by: Babcock_Hall on November 16, 2021, 02:31:14 PM
Do you want to increase pH or decrease pH?
Title: Re: Increasing water pH level
Post by: Nat360 on November 16, 2021, 04:26:20 PM
Hi. Thanks for your replies.
I was planning on dissolving a acid in water

Dissolving a solid acid, or adding acid solution. Yes, that's the correct way of decreasing pH.

Quote
but I am unsure of how to seperate the water from the acid while still maintaining the pH level.

Why do you want to separate them? Please elaborate, as I fell you are misunderstanding something here.

Also note: if you want good control of pH it is better to not just add acid/base, but to use buffers. That's how the research in different pHs is typically carried out.

My experiment was to find how changing the pH level of a solution would impact the absorption of that solution in a super absorbent polymer such as sodium polyacrylate.  Based on my learning, I know that HCl will dissociate fully in water and decrease the pH of the solution. However, the Cl will still be in the solution which would have an impact on the absorption, which would introduce another variable. Also, at this point, it is just dilute HCl and I will also need to increase the pH to make it more basic.

Do you want to increase pH or decrease pH?

I was planning on increasing it and decreasing it to find the peak pH level where maximum water is being absorbed.
Title: Re: Increasing water pH level
Post by: Corribus on November 16, 2021, 05:43:10 PM
You can't just remove one of the ions because charges have to be balanced. If you have a solution with dissolved cations, you must also have dissolved anions.
Title: Re: Increasing water pH level
Post by: ninonino on November 16, 2021, 09:45:20 PM
try add some sodium bicarbonate