HI
I was looking for the Properties of water Thread,
please add to it if there is one if not this is it.
I was doing more reading on the P and alkalinity of water and wanted to know what happens when when it boils or is split by polarization heres what I found so far I think this is basic knowledge but knowledge stan always had in his head fresh as he was in nuclear reactions info for a while
How does boiling water make it acidic?
Den asked 3 years ago
if we measure the ph of pure water at 25 degrees, we find the water has a pH of 7. then if we heat water, the pH decreases. When the water begins to boil at 100 degrees the pH is 6.12. We find ourselves faced with a paradox. On the one hand we know that the sample of water is neautral because pure water is neither acidic nor basic. on the other hand the small pH reading seems to indicate that the water sample has become acidic because the boiling water has a pH that is less than 7.
By analysing and evaluating the interrelationships between the concepts and algorithms related to ionisation of water, pH and Le Chatellier's Principle, explain how you would resolve this inconsistancy. This answer will require calculations and equations.
Temperature (oC) / Kw
0 / 1.13 x 10^-15
10 / 12.92 x 10^-15
25 / 1.00 x 10^-14
37 / 2.38 x 10^-14
45 / 4.02 x 10^-14
60 / 9.61 x 10^-14
==============================
Pure water is 7.0??? Probably not. Pure water would be in contact with the air, and pick up some CO2 which will make the solution acidic. Boiling the water will actually make it LESS acidic, since it will drive off some of the dissolved CO2.
Wait. You're talking about something entirely different, and you need to adjust your thinking about the pH that represents a neutral solution as the temperature of the solution is raised.
As you have noted, at 60C Kw = 9.61x10^-14. Since Kw = [H+][OH-], then [H+] = 3.1x10^-7 for a neutral solution, instead of the 1.00x10^-7 that we see at 25C. The solution is NOT more acidic at 60C, the pH of what is a neutral solution has changed.
Recap:
At 60C, Kw = 9.61 x 10^-14
For a neutral solution, [H+] = [OH-] = 3.1x10^-7 .... (the square root of 9.61x10^-14)
The pH which corresponds to 3.1x10^-7 is 6.51.
This pH, 6.51, therefore, represents a neutral solution at 60C, not an acidic solution.
At 60C, pH values below 6.51 are acidic, and pH values above 6.51 are basic.
===============================
Well, the pH of water is effectively the moles of the H+ ion in the solution. When water is heated, one of the H+ on the water molecule is more prone to dissociate than when the water is cold.
LeChatelier's principle states that the equilibrium will change with temperature, pressure or concentration.
and remember that pH = -log[H+]
according to the link below, the ph of boiled water will go up due to a loss of bicarbonate ions and H{++} ions. It also says that the ph will go back towards whatever it was originally but not quite make it there, resulting in the water having a permanently slight increase in its ph.
You are correct. Increasing pH is the same as 'pH goes up'. It means the solution is becoming less acidic and more alkaline. You probably already know that the pH scale runs from 0 to 14 with a pH of <7 for acidic solutions, 7 for a neutral solution and >7 for an alkaline solution. The further you are away from 7 the more acidic or alkaline the solution is ( so I like to think of it as two scales running outwards from 7 ).
http://www.hindu.com/seta/2005/08/25/stories/2005082500271600.htm
Why does the taste of water change when boiled?
C. Sabarish
Tiruvannamalai, Tamil Nadu
Potable water contains a variety of dissolved stuff that includes salts of calcium, magnesium, sodium, potassium, and the like among others besides dissolved carbon dioxide and oxygen.
The taste of such water arrives collectively from this composition and the pH (a dimension less parameter related to the concentration of H{++} ions). Even if one or two of these solutes is absent or altered, the tast e varies to that extent.
The dissolved carbon dioxide reacts with the water to give carbonic acid (H{-2}CO{-3}) which in turn dissociates reversibly to give low concentrations of hydrogen (H{++}) and bicarbonate (HCO{-3}{+-}) ions.
Thus the pH is regulated by the amounts of dissolved carbon dioxide and bicarbonate ions (of all sources).
However, the bicarbonate ions are vulnerable to heat and undergo thermolysis to give carbonate ion and carbon dioxide (as 2HCO{-3} CO{-3} + CO{-2} + H{-2}O). This and the other regular carbon dioxide, including the dissolved oxygen are expelled from water when boiled.
Even when cooled, the reentry of carbon dioxide cannot fully make up the loss of bicarbonates. All this means a reduced concentration of bicarbonate ions and H{++} ions (increased pH) and an enhancement to that of carbonate ions in boiled water. Hence, the change in the taste of boiled water (even after cooling).
There is no need to boil the water if one is sure of the absence of microorganisms in the water and there is every reason to boil and cool the water, even at the cost of losing the taste a bit, if the water is likely to contain pathogenic microorganisms.
Prof. A. Ramachandariah
Convenor, S&T, Jana Vignana Vedika
Warangal, Andhra Pradesh
http://www.elmhurst.edu/~chm/vchembook/184ph.html
Introduction and Definitions:
Acidic and basic are two extremes that describe a chemical property chemicals. Mixing acids and bases can cancel out or neutralize their extreme effects. A substance that is neither acidic nor basic is neutral.
The pH scale measures how acidic or basic a substance is. The pH scale ranges from 0 to 14. A pH of 7 is neutral. A pH less than 7 is acidic. A pH greater than 7 is basic.
The pH scale is logarithmic and as a result, each whole pH value below 7 is ten times more acidic than the next higher value. For example, pH 4 is ten times more acidic than pH 5 and 100 times (10 times 10) more acidic than pH 6. The same holds true for pH values above 7, each of which is ten times more alkaline (another way to say basic) than the next lower whole value. For example, pH 10 is ten times more alkaline than pH 9 and 100 times (10 times 10) more alkaline than pH 8.
Pure water is neutral. But when chemicals are mixed with water, the mixture can become either acidic or basic. Examples of acidic substances are vinegar and lemon juice. Lye, milk of magnesia, and ammonia are examples of basic substances.
Practice:
Ionization of Water:
Water molecules exist in equilibrium with hydrogen ions and hydroxide ions.
H2O <--> H+ + OH-
The water equilibrium constant is written as:
Kw = [H+] [OH-]
Experimentally, it has been found that the concentration of:
H+ = OH- = 10-7
Therefore: Kw = [10-7][ 10-7] = [10-14]
(To multiply exponential numbers - simply add the exponents.)
The values for Kw, H+, OH- concentration all indicate that the equilibrium favors the reactant (water molecules). In other words, only very small amounts of H+ and OH- ions are present.
Effect of Acids and Bases on Water Equilibrium:
If an acid (H+) is added to the water, the equilibrium shifts to the left and the OH- ion concentration decreases.
Water Equilibrium: H2O <--> H+ + OH-
If base ( OH-) is added to water, the equilibrium shifts to left and the H+ concentration decreases.
Water Equilibrium Principle: The multiplication product (addition of exponents) of H+ and OH- ion concentration must always be equal to 10-14.
BOTH H+ and OH- ions are ALWAYS PRESENT in any solution. A solution is acidic if the H+ are in excess. A solution is basic, if the OH- ions are in excess.
Definition of pH, pOH, and pKw:
The concentrations of hydrogen ions and indirectly hydroxide ions are given by a pH number. pH is defined as the negative logarithm of the hydrogen ion concentration. The equation is:
pH = - log [H+]
similarly, pOH = - log [OH-]
and p Kw = - log [Kw] .
Logarithms of numbers that are multiples of ten are merely the exponents of the number including the sign. See the table on the left for a review. The method to find logs of numbers that are not multiples of ten are found by using a calculator. The method is not discussed here.
Example: If an acid has an H+ concentration of 0.0001 M, find the pH.
Solution:
First convert the number to exponential notation, find the log, then solve the pH equation.
H+ = 0.0001M = 10-4; log of 10-4 = -4;
pH = - log [ H+] = - log (10-4) = - (-4) = +4 = pH
The purpose of the negative sign in the log definition is to give a
positive pH value.
Example:
If the base has an OH- concentration of 0.001M, find the pH.
Solution:
First find the pOH, (similar to finding the pH,) then subtract the pOH from 14.
OH- = 0.001M = 10-3;
pOH = -log [OH-] = -log (10-3) = +3 = pOH
pH = 14 - pOH; pH = 14 - 3 = 11 = pH
pH Principle: pH and pOH must always equal pKw (14).
pH Scale:
The pH scale, (0 - 14), is the full set of pH numbers which indicate the concentration of H+ and OH-ions in water. The diagram on the left gives some relationships which summarizes much of the previous discussion.
pH Scale Principle:
H+ ion concentration and pH relate inversely.
OH- ion concentration and pH relate directly.
The following statements may be made about the pH scale
numbers. Complete some of them.
a. Increasing pH means the H+ ions are decreasing.
b. Decreasing pH means H+ ions are increasing.
c. Increasing pH means OH- ions are
d. Decreasing pH means OH- ions are
So I still would ask if we are polarizing water for drinking the acidic side
has more h in it?
this may be a way of concentrating the pacific side and the h we want which is saturated.
For example we use micro mixers and or pezo mixers atomizers on the acidic flow
while further electolyzer thus makes more dissolved h it is temporary but work
similar to what they did in Japan
Dan
I was looking for the Properties of water Thread,
please add to it if there is one if not this is it.
I was doing more reading on the P and alkalinity of water and wanted to know what happens when when it boils or is split by polarization heres what I found so far I think this is basic knowledge but knowledge stan always had in his head fresh as he was in nuclear reactions info for a while
How does boiling water make it acidic?
Den asked 3 years ago
if we measure the ph of pure water at 25 degrees, we find the water has a pH of 7. then if we heat water, the pH decreases. When the water begins to boil at 100 degrees the pH is 6.12. We find ourselves faced with a paradox. On the one hand we know that the sample of water is neautral because pure water is neither acidic nor basic. on the other hand the small pH reading seems to indicate that the water sample has become acidic because the boiling water has a pH that is less than 7.
By analysing and evaluating the interrelationships between the concepts and algorithms related to ionisation of water, pH and Le Chatellier's Principle, explain how you would resolve this inconsistancy. This answer will require calculations and equations.
Temperature (oC) / Kw
0 / 1.13 x 10^-15
10 / 12.92 x 10^-15
25 / 1.00 x 10^-14
37 / 2.38 x 10^-14
45 / 4.02 x 10^-14
60 / 9.61 x 10^-14
==============================
Pure water is 7.0??? Probably not. Pure water would be in contact with the air, and pick up some CO2 which will make the solution acidic. Boiling the water will actually make it LESS acidic, since it will drive off some of the dissolved CO2.
Wait. You're talking about something entirely different, and you need to adjust your thinking about the pH that represents a neutral solution as the temperature of the solution is raised.
As you have noted, at 60C Kw = 9.61x10^-14. Since Kw = [H+][OH-], then [H+] = 3.1x10^-7 for a neutral solution, instead of the 1.00x10^-7 that we see at 25C. The solution is NOT more acidic at 60C, the pH of what is a neutral solution has changed.
Recap:
At 60C, Kw = 9.61 x 10^-14
For a neutral solution, [H+] = [OH-] = 3.1x10^-7 .... (the square root of 9.61x10^-14)
The pH which corresponds to 3.1x10^-7 is 6.51.
This pH, 6.51, therefore, represents a neutral solution at 60C, not an acidic solution.
At 60C, pH values below 6.51 are acidic, and pH values above 6.51 are basic.
===============================
Well, the pH of water is effectively the moles of the H+ ion in the solution. When water is heated, one of the H+ on the water molecule is more prone to dissociate than when the water is cold.
LeChatelier's principle states that the equilibrium will change with temperature, pressure or concentration.
and remember that pH = -log[H+]
according to the link below, the ph of boiled water will go up due to a loss of bicarbonate ions and H{++} ions. It also says that the ph will go back towards whatever it was originally but not quite make it there, resulting in the water having a permanently slight increase in its ph.
You are correct. Increasing pH is the same as 'pH goes up'. It means the solution is becoming less acidic and more alkaline. You probably already know that the pH scale runs from 0 to 14 with a pH of <7 for acidic solutions, 7 for a neutral solution and >7 for an alkaline solution. The further you are away from 7 the more acidic or alkaline the solution is ( so I like to think of it as two scales running outwards from 7 ).
http://www.hindu.com/seta/2005/08/25/stories/2005082500271600.htm
Why does the taste of water change when boiled?
C. Sabarish
Tiruvannamalai, Tamil Nadu
Potable water contains a variety of dissolved stuff that includes salts of calcium, magnesium, sodium, potassium, and the like among others besides dissolved carbon dioxide and oxygen.
The taste of such water arrives collectively from this composition and the pH (a dimension less parameter related to the concentration of H{++} ions). Even if one or two of these solutes is absent or altered, the tast e varies to that extent.
The dissolved carbon dioxide reacts with the water to give carbonic acid (H{-2}CO{-3}) which in turn dissociates reversibly to give low concentrations of hydrogen (H{++}) and bicarbonate (HCO{-3}{+-}) ions.
Thus the pH is regulated by the amounts of dissolved carbon dioxide and bicarbonate ions (of all sources).
However, the bicarbonate ions are vulnerable to heat and undergo thermolysis to give carbonate ion and carbon dioxide (as 2HCO{-3} CO{-3} + CO{-2} + H{-2}O). This and the other regular carbon dioxide, including the dissolved oxygen are expelled from water when boiled.
Even when cooled, the reentry of carbon dioxide cannot fully make up the loss of bicarbonates. All this means a reduced concentration of bicarbonate ions and H{++} ions (increased pH) and an enhancement to that of carbonate ions in boiled water. Hence, the change in the taste of boiled water (even after cooling).
There is no need to boil the water if one is sure of the absence of microorganisms in the water and there is every reason to boil and cool the water, even at the cost of losing the taste a bit, if the water is likely to contain pathogenic microorganisms.
Prof. A. Ramachandariah
Convenor, S&T, Jana Vignana Vedika
Warangal, Andhra Pradesh
http://www.elmhurst.edu/~chm/vchembook/184ph.html
Introduction and Definitions:
Acidic and basic are two extremes that describe a chemical property chemicals. Mixing acids and bases can cancel out or neutralize their extreme effects. A substance that is neither acidic nor basic is neutral.
The pH scale measures how acidic or basic a substance is. The pH scale ranges from 0 to 14. A pH of 7 is neutral. A pH less than 7 is acidic. A pH greater than 7 is basic.
The pH scale is logarithmic and as a result, each whole pH value below 7 is ten times more acidic than the next higher value. For example, pH 4 is ten times more acidic than pH 5 and 100 times (10 times 10) more acidic than pH 6. The same holds true for pH values above 7, each of which is ten times more alkaline (another way to say basic) than the next lower whole value. For example, pH 10 is ten times more alkaline than pH 9 and 100 times (10 times 10) more alkaline than pH 8.
Pure water is neutral. But when chemicals are mixed with water, the mixture can become either acidic or basic. Examples of acidic substances are vinegar and lemon juice. Lye, milk of magnesia, and ammonia are examples of basic substances.
Practice:
Ionization of Water:
Water molecules exist in equilibrium with hydrogen ions and hydroxide ions.
H2O <--> H+ + OH-
The water equilibrium constant is written as:
Kw = [H+] [OH-]
Experimentally, it has been found that the concentration of:
H+ = OH- = 10-7
Therefore: Kw = [10-7][ 10-7] = [10-14]
(To multiply exponential numbers - simply add the exponents.)
The values for Kw, H+, OH- concentration all indicate that the equilibrium favors the reactant (water molecules). In other words, only very small amounts of H+ and OH- ions are present.
Effect of Acids and Bases on Water Equilibrium:
If an acid (H+) is added to the water, the equilibrium shifts to the left and the OH- ion concentration decreases.
Water Equilibrium: H2O <--> H+ + OH-
If base ( OH-) is added to water, the equilibrium shifts to left and the H+ concentration decreases.
Water Equilibrium Principle: The multiplication product (addition of exponents) of H+ and OH- ion concentration must always be equal to 10-14.
BOTH H+ and OH- ions are ALWAYS PRESENT in any solution. A solution is acidic if the H+ are in excess. A solution is basic, if the OH- ions are in excess.
Definition of pH, pOH, and pKw:
The concentrations of hydrogen ions and indirectly hydroxide ions are given by a pH number. pH is defined as the negative logarithm of the hydrogen ion concentration. The equation is:
pH = - log [H+]
similarly, pOH = - log [OH-]
and p Kw = - log [Kw] .
Logarithms of numbers that are multiples of ten are merely the exponents of the number including the sign. See the table on the left for a review. The method to find logs of numbers that are not multiples of ten are found by using a calculator. The method is not discussed here.
Example: If an acid has an H+ concentration of 0.0001 M, find the pH.
Solution:
First convert the number to exponential notation, find the log, then solve the pH equation.
H+ = 0.0001M = 10-4; log of 10-4 = -4;
pH = - log [ H+] = - log (10-4) = - (-4) = +4 = pH
The purpose of the negative sign in the log definition is to give a
positive pH value.
Example:
If the base has an OH- concentration of 0.001M, find the pH.
Solution:
First find the pOH, (similar to finding the pH,) then subtract the pOH from 14.
OH- = 0.001M = 10-3;
pOH = -log [OH-] = -log (10-3) = +3 = pOH
pH = 14 - pOH; pH = 14 - 3 = 11 = pH
pH Principle: pH and pOH must always equal pKw (14).
pH Scale:
The pH scale, (0 - 14), is the full set of pH numbers which indicate the concentration of H+ and OH-ions in water. The diagram on the left gives some relationships which summarizes much of the previous discussion.
pH Scale Principle:
H+ ion concentration and pH relate inversely.
OH- ion concentration and pH relate directly.
The following statements may be made about the pH scale
numbers. Complete some of them.
a. Increasing pH means the H+ ions are decreasing.
b. Decreasing pH means H+ ions are increasing.
c. Increasing pH means OH- ions are
d. Decreasing pH means OH- ions are
So I still would ask if we are polarizing water for drinking the acidic side
has more h in it?
this may be a way of concentrating the pacific side and the h we want which is saturated.
For example we use micro mixers and or pezo mixers atomizers on the acidic flow
while further electolyzer thus makes more dissolved h it is temporary but work
similar to what they did in Japan
Dan