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Posted on Jan 02, 2017

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pH=-log[concentration of H+ ions]

Feb 18, 2014 | Texas Instruments TI-34 Scientific...

pH values are the acidity of a body of water. Neutral water has a value of 7.0 meaning that it has equal amounts of hydrogen ions and hydroxide ions. When more hydrogen ions are added the water then the number goes down and the water becomes more acidic, or if the amount of hydroxide ions goes up then the water becomes more alkaline.

pH levels in your fish tank can prove to be fatal if they aren't monitored properly. While there is no secret formula for the perfect pH level for all fish it is best to keep all the fish from the same bodies of water together. Salt water fish shouldn't be put in a tank with freshwater fish because they need different pH levels.

Throughout the day the pH level of your fish tank will change although these slight changes shouldn't be too harmful on your fish sudden changes will prove to be fatal. When you are moving fish from one tank to another you want to make sure that the two waters have the same pH levels. When you want to buy a new fish check the pH level of your fish tank and then the pH level of the water at the pet shop to make sure that the levels are not too different.

You should be checking the pH levels of your fish tank at least once a month, but more often is always better. When you take the pH level you should write it down in a log book. You should try to take the pH level at the same time every time you take a reading because at different times of the day the levels would be different. Try to keep yourself from going crazy, if the pH level is a few decimals off of perfect your fish will be okay. If the level is fairly regular you shouldn't have to do anything unless your fish show signs of distress.

pH levels in your fish tank can prove to be fatal if they aren't monitored properly. While there is no secret formula for the perfect pH level for all fish it is best to keep all the fish from the same bodies of water together. Salt water fish shouldn't be put in a tank with freshwater fish because they need different pH levels.

Throughout the day the pH level of your fish tank will change although these slight changes shouldn't be too harmful on your fish sudden changes will prove to be fatal. When you are moving fish from one tank to another you want to make sure that the two waters have the same pH levels. When you want to buy a new fish check the pH level of your fish tank and then the pH level of the water at the pet shop to make sure that the levels are not too different.

You should be checking the pH levels of your fish tank at least once a month, but more often is always better. When you take the pH level you should write it down in a log book. You should try to take the pH level at the same time every time you take a reading because at different times of the day the levels would be different. Try to keep yourself from going crazy, if the pH level is a few decimals off of perfect your fish will be okay. If the level is fairly regular you shouldn't have to do anything unless your fish show signs of distress.

on Feb 02, 2014 | Measuring Tools & Sensors

the p stands for potential and the H stands for Hydrogen, and it refers to the ability to attract hydrogen ions.

Jan 28, 2013 | Measuring Tools & Sensors

The pH scale is a logarithmic scale used to measure the concentrations of hydrogen/Hydronium ions in an aqueous solution.

If c[H] is the concentration of hydrogen ions in mol/L, the pH is defined as

pH=-log(c[H]).

Inversely, the concentration is given by

c[H]=10^(-pH)

The pOH=14-pH

If c[H] is the concentration of hydrogen ions in mol/L, the pH is defined as

pH=-log(c[H]).

Inversely, the concentration is given by

c[H]=10^(-pH)

The pOH=14-pH

Jan 19, 2012 | Office Equipment & Supplies

pH is defined as the negative logarithm of the hydrogen ion activity in a solution:

The value is defined as the molar concentration of H+ Ions, multiplied by a correction factor, the activity coefficient. The activity coefficient is required because in nature there are rarely actual H+ ions in a solution. For example, in water H+ ions combine with water molecules to Oxonium and Hydronium ions:

The associated products are less reactive than H+ ions would be, so the activity coefficient is always greater than 0 and smaller than 1. It depends on plenty of factors, e.g. the temperature of the solution, or the presence of other substances, and is very difficult to determine precisely.

For this reason, in water solutions the pH is usually approximated by:

for other solutions (not in water), similar approaches exist, but the resulting "pH" equivalents are not directly comparable.

Long story short: get the H3O+ concentration in mol/L by measuring it, or from the problem text. For example, if the concentration is 0.003 mol/L, key in:

and get a pH of 2.52

The value is defined as the molar concentration of H+ Ions, multiplied by a correction factor, the activity coefficient. The activity coefficient is required because in nature there are rarely actual H+ ions in a solution. For example, in water H+ ions combine with water molecules to Oxonium and Hydronium ions:

The associated products are less reactive than H+ ions would be, so the activity coefficient is always greater than 0 and smaller than 1. It depends on plenty of factors, e.g. the temperature of the solution, or the presence of other substances, and is very difficult to determine precisely.

For this reason, in water solutions the pH is usually approximated by:

for other solutions (not in water), similar approaches exist, but the resulting "pH" equivalents are not directly comparable.

Long story short: get the H3O+ concentration in mol/L by measuring it, or from the problem text. For example, if the concentration is 0.003 mol/L, key in:

and get a pH of 2.52

Feb 02, 2011 | Texas Instruments TI-30XA Calculator

I suggest you reformulate the question. If you are doing pH questions, give the pH and we will show you how to get the concentration. Alternatively, give the concentration and we will show you how to obtain the pH. Keep in mind that in the context of pH questions, pH is restricred to the interval [0,14], and that imposes restrictions on the possible values of the concentration.

If c=concentartion, then

pH=-log(c)

This is equivalent to

c=10^(-pH)

Assuming that this is what you want to do (ie. calculate the concentration)

Press [2nd][log] to access the 10^ function

Screen displays 10^(

Enter the change sign [+/-]

Enter the pH value 4.62

Screen displays 10^( -4.62)

Press [=]

The result is 2.398832919E-05. To 3 significant digits the concentartion is c=2.39E-05 mol/L of H+/H3O+ ion

If c=concentartion, then

pH=-log(c)

This is equivalent to

c=10^(-pH)

Assuming that this is what you want to do (ie. calculate the concentration)

Press [2nd][log] to access the 10^ function

Screen displays 10^(

Enter the change sign [+/-]

Enter the pH value 4.62

Screen displays 10^( -4.62)

Press [=]

The result is 2.398832919E-05. To 3 significant digits the concentartion is c=2.39E-05 mol/L of H+/H3O+ ion

Mar 07, 2010 | Casio FX-115ES Scientific Calculator

Hello,

This post answers two questions

As you well know the pH is the negative of the log in base 10 of the H+/H3O+ ion concentration. If we use [H+] to represent that concentration, then**pH=-log[H+]**.

To obtain the [H+] you need to calculate the antilog. You write the definition in the form**log[H+] =-pH **and then calculate 10 to the power of each member. The equality remains valid as both members are treated similarly. Thus

10^( log[H+] ) = 10^(-pH)

Since raising 10 to a power is the inverse function of taking the log in base 10, 10^(log(x))=log(10^(x)) = x (they are inverse of one another), you are left with

**[H+]=10^(-pH)**

Your calculator has a function [10 to x] accessed by pressing the [2nd] function key. **To use it you must enter the negative value of the pH, press the ** [2nd] function key then the [10 to x], then the = key to get the result (concentration)

**Example**s

1. Let the pH=5.5, what is the H+ concentration?

With [(-)] being the change sign key, then

[H+]:**[ (-) ] 5.5 [2nd][10 to x] [=] **

The result is 0.000003162 or 3.16 x 10^(-6)

Calculating the pH

Shortcut:

For all H+/H3O+ concentrations of the form**1.*10^(a)** where a is** an integer number between 0 and -14**, the pH is the negative value of the exponent.

Concentration =10^(-3), pH=3

Concentration=10^(-11), pH=11

For other concentrations such as 3.567*10^(-8), one cannot use the shortcut above, but have to calculate the log of the concentration

[H+/H3O+] = 3.567*10^(-8)

pH= - log(3.567*10^(-8))

This is keyed in as follows (to minimize the number of parentheses)

**8 (-) [2nd][10 to x] [*] 3.567 [LOG] [=] (-)**

Here you have two (-) change sign, the first is entered after the exponent of 10, the other at the end of the calculation to take the negative of the displayed result.**You may notice that it is entered in the reverse order of the defining relation **- log(3.567*10^(-8)).

To verify your calculation, the result is 7.447696891 or just 7.45

If you have a problem with the first (-) try entering it before you type in 8.

Hope it helps** **and thank you for using FixYa

And please, show your appreciation by rating the solution**.**

This post answers two questions

- How to obtain the concentration knowing the pH?
- How to obtain the pH knowing the concentration

As you well know the pH is the negative of the log in base 10 of the H+/H3O+ ion concentration. If we use [H+] to represent that concentration, then

To obtain the [H+] you need to calculate the antilog. You write the definition in the form

10^( log[H+] ) = 10^(-pH)

Since raising 10 to a power is the inverse function of taking the log in base 10, 10^(log(x))=log(10^(x)) = x (they are inverse of one another), you are left with

1. Let the pH=5.5, what is the H+ concentration?

With [(-)] being the change sign key, then

[H+]:

Calculating the pH

For all H+/H3O+ concentrations of the form

Concentration =10^(-3), pH=3

Concentration=10^(-11), pH=11

For other concentrations such as 3.567*10^(-8), one cannot use the shortcut above, but have to calculate the log of the concentration

[H+/H3O+] = 3.567*10^(-8)

pH= - log(3.567*10^(-8))

This is keyed in as follows (to minimize the number of parentheses)

Here you have two (-) change sign, the first is entered after the exponent of 10, the other at the end of the calculation to take the negative of the displayed result.

To verify your calculation, the result is 7.447696891 or just 7.45

If you have a problem with the first (-) try entering it before you type in 8.

Dec 07, 2009 | Texas Instruments TI-30XA Calculator

Hello,

As you well know the pH is the negative of the log in base 10 of the H+/H3O+ ion concentration. If we use [H+] to represent that concentration, then**pH=-log[H+]**.

To obtain the [H+] you need to calculate the antilog. You write the definition in the form**log[H+] =-pH **and then calculate 10 to the power of each member. The equality remains valid as both members are treated similarly. Thus

10^( log[H+] ) = 10^(-pH)

Since raising 10 to a power is the inverse function of taking the log in base 10, 10^(log(x))=log(10^(x)) = x (they are inverse of one another), you are left with

**[H+]=10^(-pH)**

Your calculator has a function [10 to x] accessed by pressing the [2nd] function key. **To use it you must enter the negative value of the pH, press the ** [2nd] function key then the [10 to x], then the = key to get the result (concentration)

Exemple: let the pH=5.5, what is the H+ concentration?

With [(-)] being the change sign key, then

[H+]:**[ (-) ] 5.5 [2nd][10 to x] [=] **

The result is 0.000003162 or 3.16 x 10^(-6)

Hope it helps.

As you well know the pH is the negative of the log in base 10 of the H+/H3O+ ion concentration. If we use [H+] to represent that concentration, then

To obtain the [H+] you need to calculate the antilog. You write the definition in the form

10^( log[H+] ) = 10^(-pH)

Since raising 10 to a power is the inverse function of taking the log in base 10, 10^(log(x))=log(10^(x)) = x (they are inverse of one another), you are left with

Exemple: let the pH=5.5, what is the H+ concentration?

With [(-)] being the change sign key, then

[H+]:

Dec 07, 2009 | Texas Instruments TI-30XA Calculator

It should be this sequence:

2.9 {EE} 4 {+ -> -} will give you the Sci.Not.

Then {=} (0.00029)

Then {LOG} (-3.537602002)

Then {+ -> -} (3.537602002)

pH=3.54

2.9 {EE} 4 {+ -> -} will give you the Sci.Not.

Then {=} (0.00029)

Then {LOG} (-3.537602002)

Then {+ -> -} (3.537602002)

pH=3.54

Feb 25, 2009 | Texas Instruments TI-30XA Calculator

pH is minus (log to base 10) of the hydrogen ion activity of an aqueous solution, or (log to base 10) of (1/hydrogen ion activity)

To get the inverse log, i.e the hydrogen ion activity corresponding to a specified pH, simply enter the pH value and press

2nd

LOG

1/x

Answer 0.001

To get the inverse log, i.e the hydrogen ion activity corresponding to a specified pH, simply enter the pH value and press

2nd

LOG

1/x

Answer 0.001

Apr 22, 2008 | Texas Instruments TI-30XA Calculator

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