pH of Pure Water at 100°C | Acids & Bases

In summary, the value of Kw, the ionic product of water, increases with temperature. At 100*C, the pH of pure water will be slightly more acidic, around 6.87. This is due to the increase in the ionic product and the absorption of CO2, leading to the formation of carbonic acid.
  • #1
Jack16
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Could You Help Me Out Please...

The Value of Kw ,the ionic product of water,increases with temperature.Will the pH of pure water be greater or less than 7 at 100*C?
 
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  • #2
Hello,

It will be slightly more acidic, although H+ and OH- will be equally dissociated from water; because pH is calculated according to [H+]. Let me assume that in a higher temperature, the ionic product changes to 1,8.10-14. When you calculate the -log value of this, you'll find ca. 6,87. This shows that the pH value will be lower in higher temperatures.

In addition, in a higher temperature, the absorption of CO2 will be much higher, then the formation of carbonic acid, H2CO3, will cause the resulting aqueous solution to be even more acidic than that in the ambient temperature.

Regards, chem_tr
 
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  • #3


At 100°C, the pH of pure water will be less than 7. This is because as the temperature increases, the value of Kw also increases, resulting in a higher concentration of hydrogen ions (H+) and a lower concentration of hydroxide ions (OH-). This shift in the equilibrium of the dissociation of water molecules leads to a decrease in pH, making the solution more acidic. Therefore, at 100°C, the pH of pure water will be less than 7.
 

1. What is the pH of pure water at 100°C?

The pH of pure water at 100°C is approximately 6.14. This is considered to be neutral, as it is close to the pH of 7 which is considered neither acidic nor basic.

2. How does the pH of pure water at 100°C compare to that at room temperature?

The pH of pure water at 100°C is lower than at room temperature. This is because at higher temperatures, water molecules are more likely to dissociate into hydrogen ions and hydroxide ions, leading to a decrease in pH.

3. Is pure water at 100°C considered to be an acid or a base?

Pure water at 100°C is considered to be neutral, as it has a pH of 6.14. However, it can also be classified as a weak acid, as it has a slightly lower pH than 7.

4. How does the pH of pure water at 100°C change when an acid or base is added?

The pH of pure water at 100°C will change depending on the type and concentration of the acid or base added. If a strong acid is added, the pH will decrease and become more acidic. Conversely, if a strong base is added, the pH will increase and become more basic.

5. Why is it important to know the pH of pure water at 100°C?

The pH of pure water at 100°C is important because it can affect the properties and reactions of other substances. It also provides a reference point for comparing the pH of other solutions at high temperatures. Additionally, understanding the pH of pure water at different temperatures is crucial for various industrial and scientific processes.

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