■ pH scale
► | A numerical scale that has a range between 0 to 14. | |
► | To measure the acidity and alkalinity of a solution. | |
► | A measurement of the H+ ion in a solution. (pH = -log[H+]) | |
► | Definition : -log[H+], where [H+] represents the concentration of hydrogen ion. |
► | An aqueous solution contains hydrogen ions, H+ and hydroxide ion, OH- formed from the dissociation of water. | |||||||||||||
► | pH scale can be used to compare the concentration of hydrogen ion, H+ in an acidic solution. | |||||||||||||
► | pH scale can be used to compare the concentration of hydroxide ion, OH- in an alkaline solution.
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► | The animation below shows the relationship between hydrogen ions, H+ and hydroxide ion, OH-.
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► | Universal indicator
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► | pH meter
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Degree of dissociation of acids in water
■ Degree of dissociation/ionisation
► | Strength of an acid or an alkalinity. | |
► | Percentage or fraction of molecules that dissociates into ion when dissolved in water. |
► | Strong acid: an acid dissociates completely in water to form hydrogen ion, H+ of high concentration. | |
► | Weak acid: an acid dissociates partially in water to produce hydrogen ion, H+, of low concentration. |
► | Strong acids and weak acids have the same chemical properties but the rate of reaction and electrical conductivity of weak acid is lower. | ||||||||||||||||
► | Weak acid: an acid dissociates partially in water to produce hydrogen ion, H+, of low concentration.
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Degree of dissociation of alkalis in water
■ Alkalis can be divided into two categories:-
► | Strong alkalis: an alkali dissociates completely in water to form hydroxide ion, OH- of high concentration. | |
► | Weak alkalis: an alkali dissociates partially in water to produce hydroxide ion, OH- of low concentration. |
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⇲ For exercise(objective and subjective), download for free on Android OS. | ||
thank you for your information
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