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pH Value

 
6.2 pH Value
 
The pH Scale

  • The pH scale is a set of number that determines the degree of acidity or alkalinity of a substance.
  • The pH value would be:
    • 7 for neutral substance.
    • > 7 for alkaline substance (\(OH^- > H^+\))
    • < 7 for acidic substance (\(H^+ > OH^-\))

 

\(\xleftarrow[]{\textbf{Acidity } \uparrow}\) Neutral \(\xrightarrow[]{\textbf{Alkalinity } \uparrow}\)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

 
 
Definition of pH
a logarithmic measurement of the concentration of hydrogen ions, š»+ contained in an aqueous solution.
 
Formula of pH
\(pH = -log[H^+]\)
 
Concentration of Hydroxide Ions, \(OH^-\)
Is used to calculate the pOH value.
 
Formula of pOH
\(pOH = -log[OH^-]\)
 
Hubungan pH dan pOH

\(pH + pOH=14\)

                             \(pH=14 - pOH\)
 
Relationship of pH value with Concentration of Hydrogen Ion and Hydroxide Ion
Relationship of concentration \(H^+\) with pH
           
  Concentration \(H^+\) \(\uparrow\), pH value \(\downarrow\)  
           
Relationship of Concentration \(OH^-\) with pH
           
  Concentration \(OH^-\) \(\uparrow\), pH value \(\uparrow\)  
           
 
Measurement of the pH Value of A Solution
Apparatus for Measuring pH Values

The image features a cartoon illustration of a person with a label above their head that reads ā€˜Apparatus to Measure pH Value.ā€™ There are two arrows pointing downwards from the label to two boxes. The box on the left is labeled ā€˜Universal indicator,ā€™ and the box on the right is labeled ā€˜pH meter.ā€™ The logo ā€˜Pandaiā€™ is present in the top left corner.
Universal Indicator
  • The universal indicator will change colour, and it indicates what the pH based on the colour produced is.
  • The universal indicator can be found in two forms; solution or paper strips. 
pH Meter
  • The pH meter is an instrument that is used to measure the pH value of a solution accurately.
  • pH meter shows the number of the pH value in the screen.
 
The pH Value of Few Items in Daily LifeTested with the Universal Indicator
Material pH Value
Battery 0
Gastric juice 1
Lemon 2
Vinegar 3
Tomato 4
Coffee 5
Milk 6
Water 7
Blood 8
Baking soda 9
Antacid 10
Ammonia solution 11
Soap 12
Bleach 13
Sewage pipe cleaner 14
 

 

 

 

 

 

The views expressed in the notes here are those of the contributor and donā€™t necessarily represent the views of Pandai.

pH Value

 
6.2 pH Value
 
The pH Scale

  • The pH scale is a set of number that determines the degree of acidity or alkalinity of a substance.
  • The pH value would be:
    • 7 for neutral substance.
    • > 7 for alkaline substance (\(OH^- > H^+\))
    • < 7 for acidic substance (\(H^+ > OH^-\))

 

\(\xleftarrow[]{\textbf{Acidity } \uparrow}\) Neutral \(\xrightarrow[]{\textbf{Alkalinity } \uparrow}\)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

 
 
Definition of pH
a logarithmic measurement of the concentration of hydrogen ions, š»+ contained in an aqueous solution.
 
Formula of pH
\(pH = -log[H^+]\)
 
Concentration of Hydroxide Ions, \(OH^-\)
Is used to calculate the pOH value.
 
Formula of pOH
\(pOH = -log[OH^-]\)
 
Hubungan pH dan pOH

\(pH + pOH=14\)

                             \(pH=14 - pOH\)
 
Relationship of pH value with Concentration of Hydrogen Ion and Hydroxide Ion
Relationship of concentration \(H^+\) with pH
           
  Concentration \(H^+\) \(\uparrow\), pH value \(\downarrow\)  
           
Relationship of Concentration \(OH^-\) with pH
           
  Concentration \(OH^-\) \(\uparrow\), pH value \(\uparrow\)  
           
 
Measurement of the pH Value of A Solution
Apparatus for Measuring pH Values

The image features a cartoon illustration of a person with a label above their head that reads ā€˜Apparatus to Measure pH Value.ā€™ There are two arrows pointing downwards from the label to two boxes. The box on the left is labeled ā€˜Universal indicator,ā€™ and the box on the right is labeled ā€˜pH meter.ā€™ The logo ā€˜Pandaiā€™ is present in the top left corner.
Universal Indicator
  • The universal indicator will change colour, and it indicates what the pH based on the colour produced is.
  • The universal indicator can be found in two forms; solution or paper strips. 
pH Meter
  • The pH meter is an instrument that is used to measure the pH value of a solution accurately.
  • pH meter shows the number of the pH value in the screen.
 
The pH Value of Few Items in Daily LifeTested with the Universal Indicator
Material pH Value
Battery 0
Gastric juice 1
Lemon 2
Vinegar 3
Tomato 4
Coffee 5
Milk 6
Water 7
Blood 8
Baking soda 9
Antacid 10
Ammonia solution 11
Soap 12
Bleach 13
Sewage pipe cleaner 14
 

 

 

 

 

 

The views expressed in the notes here are those of the contributor and donā€™t necessarily represent the views of Pandai.
Chapter : Acids, Bases and Salts
Topic : Investigate the relationship between pH value and the concentration of hydrogen and hydroxide ions through experiment
Form 4 Chemistry
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