What pH is salt water?
Does dissolving salt in water change the pH?
I am particularly interested in the effect or lack of effect of dissolved NaCl in regards to pH in water. It would be interesting also if anyone has any insight for other salts and their effects. thanks.
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asked Sep 5, 2015 at 4:31
CognisMantis CognisMantis
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$endgroup$
$begingroup$ To a first approximation the answer is no, but I’d be curious to see if someone can pull up a more precise answer, taking into account the finite values of the acidity/basicity constants and ionic strength of the medium. $endgroup$
Sep 5, 2015 at 5:10
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$begingroup$
When you dissolve a salt in water, you have to distinguish 4 cases:
- The salt results from the reaction of a strong acid with a strong base, the pH will be 7. This is the case, for example, of $ce$ that results from the reaction of $ce$ and $ce$. The ions $ce$ and $ce$ are spectator ions and don’t react with water. So, the pH doesn’t change.
- The salt results from the reaction of a strong acid with a weak base, the pH will be less than 7. This is the case , for example, of $ce$ that results from the reaction of $ce$ and $ce$. The ions $ce$ are spectator ions and don’t react with water. While the ions $ce$ do hydrolyze and give ions $ce$ to water. So, the pH will decrease.
- The salt results from the reaction of a weak acid with a strong base, the pH will be more than 7. This is the case , for example, of $ce$ that results from the reaction of $ce$ and $ce$. The ions $ce$ are spectator ions and don’t react with water. While the ions $ce$ do hydrolyze and accept ions $ce$ from water. In this case, water act as an acid leaving a hydroxide ion. So, the pH will increase.
- The salt results from the reaction of a weak acid with a weak base, the calculus of pH is a little bit complex. We need to take into consideration the $K_a$ and the $K_b$ of the weak acid and the weak base and whichever is the stronger acid or weak will be the dominate factor in determining whether the solution is acidic or basic. We can investigate three cases:
- $K_a= K_b$, the aqueous solution is neutral. This is the case, for example, of $ce$ that results from the reaction of $ce$ and $ce$. The ions $ce$ and $ce$ do hydrolyze. As the hydrolysis constant of ion acetate equals the hydrolysis constant of ion ammonium, the same concentarion of ion hydronium and ion hydroxide is produced, and the pH of the solution is neutral.
- $K_a> K_b$ This is the case, for example, of $ce$ that results from the reaction of $ce$ and $ce$. The ions $ce$ and $ce$ do hydrolyze and as ammonium ions hydrolyze to a greater extent than fluoride ions, i.e more hydronium ion is produced, and the pH of the solution is acidic.
- $K_a< K_b$ This is the case, for example, of $ce$ that results from the reaction of $ce$ and $ce$. The ions $ce$ and $ce$ do hydrolyze and as cyanide ions hydrolyze to a greater extent than fluoride ions, i.e less hydronium ions are produced, and the pH of the solution is basic.
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answered Sep 5, 2015 at 8:15
Yomen Atassi Yomen Atassi
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$endgroup$
$begingroup$$ce$ is a salt of a strong acid and strong base. As you know, strong acids give weak conjugate bases and strong bases give weak conjugate acids. Hence, the $ce$ ions are too weak to accept protons from water and $ce$ ions are to weak to react with $ce$. So there is no change in the concentration of $ce$ or $ce$, so no change in pH.
But of a salt like $ce$ is added, $ce$ accepts protons and changes pH. This is because, weak acid $ce$ gives strong conjugate base $ce$.
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answered Sep 5, 2015 at 5:01
Aditya Dev Aditya Dev
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$endgroup$- inorganic-chemistry
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Gargling With Salt Water for Oral Health
Did you know that salt inhibits the growth of bacteria and has been used for health purposes since 1600BC ? While many people rely on alcohol-based mouthwashes for oral health, there are certain times when gargling with salt water may be more beneficial, especially if you’ve had recent dental work.
Gargling With Salt Water for Oral Health
Salt increases the pH levels of the mouth, making it hostile to bacteria. This is because the mouth is acidic with an average pH of between 6.2 and 7.6 . A pH of 7 is considered neutral. PH levels below 7 are considered acidic, and pH levels above 7 are considered more alkaline. When the mouth is acidic, it contributes to bacteria growth. When salt water is gargled, it makes the mouth more alkaline, and bacteria can’t survive. When it comes to the health of your mouth, regularly gargling with salt water can help improve your oral health and reduce your risk of developing certain oral health conditions.
Salt Water Improves Your Gum Health
Gum inflammation and infections in the mouth start with excess bacteria buildup. As the bacteria in the mouth increases, the mucus membranes in the mouth as well as the gums become inflamed. Since salt helps reduce inflammation and inhibits bacterial growth, gargling with salt water and rinsing your mouth with warm salt water can help improve your overall oral health.
Salt Water Reduces Your Risk of Developing Gingivitis
Gingivitis is the early stage of gum disease. It starts with gum inflammation due to excess bacteria buildup in the mouth. Once the inflammation starts, you may notice your gums turning from pink to red. Next, you will notice that your gums bleed when you brush and/or floss your teeth. If gingivitis isn’t treated, it can lead to gum recession and periodontal disease. In order to inhibit the growth of bacteria in the mouth that can lead to gum inflammation and gingivitis, you may want to consider gargling with warm salt water a few times a week to prevent excess bacteria.
Why Salt Water Rinses Are Useful for Dental Care
When you think of maintaining and improving your oral health, you may consider using an alcohol-based mouthwash to kill bacteria in your mouth. While using mouthwash, especially alcohol-based mouthwashes, are useful in killing bacteria, they can cause irritation of the mucus membranes and gums. Alcohol also has a drying effect, which isn’t good for your mouth. While using alcohol-based mouthwashes is beneficial, you may also benefit by supplementing your oral hygiene routine with a salt water rinse, which is completely natural, especially when you consider that the human body is composed of between .3 and .4 percent salt water .
When it comes to oral health, salt water rinses work well for:
- Healing Gum Sores and Small Cuts in the Mouth
- Reducing the Risk of Infection After Dental Procedures
- Helping with Pain, Inflammation and Bacterial Infestation During Sore Throats
How Much Salt Should You Use to Gargle
When gargling and rinsing your mouth with salt water, you don’t need to add that much salt. We recommend using 1/4 teaspoon in half a cup or four ounces of water. Make sure to stir the mixture thoroughly. Then, rinse or gargle the salt water as normal. For a sore throat, it’s recommended to gargle the salt water between two and four times per day. If you have a mouth sore, a cut in your mouth or recent dental work, you can rinse your mouth two to three times a day or as needed to control pain and inflammation. If you are uncertain as to how many times a day you should rinse your mouth after dental work or if you have a sore, you can always contact Williams and Daily for further instructions and to answer your questions.
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