How do I lower the pH of a water supply

In summary, the conversation revolves around finding the appropriate amount of acid to reduce the pH of a water supply from 9.93 to 6. The equation M1V1+M2V2=M3V3 is used, with M1 representing the initial pH, V1 representing the volume of water, M2 representing the pH of the acid solution, V2 representing the volume of acid solution needed, M3 representing the desired final pH, and V3 representing the total volume after mixing. However, the exact composition of the solution is unknown and it is not possible to accurately calculate the amount of acid needed without this information.
  • #1
Biffinator87
24
1
Moved from a technical forum, so homework template missing

Homework Statement


[/B]
Just a general question to see if I'm doing this right. The volume just doesn't seem right. Anyways we have a water supply of 1.6 million gallons with a pH of 9.93. We want to get the water to a pH of 6 using a 30% HCl solution.

Homework Equations



M1V1+M2V2=M3V3

M1=9.93pH or 10-9.93
V1=1.6 million gallons or 6056656 liters
M2=pH of 30% HCl or molarity of 10.2
V2=Volume of HCl (What I want to find)
M3=6.00pH or 10-6
V3=V1+v2

The Attempt at a Solution



I also converted into liters. I assumed a molarity of 30% HCl to be around 10.2 and I assumed that V3=V1+V2

(1.17486x10-10)(6056656 liters)+(10.2)(V2)=(1.0x10-6)(6056656+V2)

Manipulating the equation to solve I ended up with a volume of approximately 0.6 liters of HCl needed to reduce the pH. It just seems like a very small amount of acid in order to handle that much water.ANY help at all is greatly appreciated.
 
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  • #2
Looking just at dilutions - your final volume is 6×107 L, expected H+ concentration is of the 10-7 order, so the volume of around 1 L doesn't sound off.

But I am afraid it is completely off. It is not just about dilution. You can't calculate how much acid is needed not knowing WHY the pH is not neutral. Acid added has to react with the base present, and most likely it has to overcome a buffering effect of whatever is dissolved in the water. No way to deal with the problem without knowing the exact composition of the solution (or some combined parameter like alkalinity of the solution).
 
  • #3
Borek said:
Looking just at dilutions - your final volume is 6×107 L, expected H+ concentration is of the 10-7 order, so the volume of around 1 L doesn't sound off.

But I am afraid it is completely off. It is not just about dilution. You can't calculate how much acid is needed not knowing WHY the pH is not neutral. Acid added has to react with the base present, and most likely it has to overcome a buffering effect of whatever is dissolved in the water. No way to deal with the problem without knowing the exact composition of the solution (or some combined parameter like alkalinity of the solution).
I was afraid of that. This is a leachate pond example so there is all kinds of stuff flowing into the pond from landfill waste. So there could be any number of things going in there. Thank you for the help!
 

1. How does the pH of water affect its quality?

The pH of water is a measure of its acidity or basicity. Water with a low pH (below 7) is considered acidic, while water with a high pH (above 7) is considered basic. This can affect the taste, smell, and overall quality of the water. Water with a pH that is too low or too high can also be harmful to human health.

2. What are some methods for lowering the pH of water?

There are several ways to lower the pH of water, including adding acidifying agents such as citric acid or vinegar, using ion exchange resins, or using specialized filtration systems. The most effective method will depend on the initial pH level and other factors, so it is best to consult a professional for the appropriate treatment method.

3. Can I use household products to lower the pH of my water supply?

While some household products like vinegar or lemon juice may temporarily lower the pH of water, they are not recommended for long-term use. These products are not specifically designed for water treatment and may not be effective or safe in the long run. It is best to consult a professional or use specialized water treatment products.

4. What are the potential risks of lowering the pH of water?

Lowering the pH of water can be beneficial for some purposes, such as reducing scaling in pipes, but it can also have negative effects. Water with a low pH can be corrosive and damage plumbing systems, and can also have adverse effects on aquatic life if discharged into streams or other bodies of water. It is important to carefully monitor and control the pH levels to avoid any potential risks.

5. How often should I test and adjust the pH of my water supply?

The frequency of testing and adjusting the pH of water will depend on various factors such as the initial pH level, water source, and intended use. In general, it is recommended to test the pH at least once a month and make adjustments as needed. If there are any changes in the water source or noticeable changes in the water quality, more frequent testing may be necessary.

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