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Strong and weak acids
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Strong and concentrated do not mean the same thing. pH depends on the concentration of hydrogen ions.
Strong and weak
A strong acid is fully ionised in water: hydrochloric, nitric, sulfuric.
A weak acid is only partially ionised: ethanoic, citric, carbonic.
A weak acid is only partially ionised: ethanoic, citric, carbonic.
Concentrated and dilute
Concentration is how much acid is dissolved in a volume of water.
You can have a dilute solution of a strong acid or a concentrated solution of a weak one.
You can have a dilute solution of a strong acid or a concentrated solution of a weak one.
pH and hydrogen ions
As the hydrogen ion concentration increases by a factor of 10, the pH decreases by 1.
pH 2 has 10 times the H+ concentration of pH 3, and 100 times that of pH 4.
pH 2 has 10 times the H+ concentration of pH 3, and 100 times that of pH 4.
pH changes from 5 to 2. By what factor has the hydrogen ion concentration increased?
- 3 pH units lower
- 10 × 10 × 10
Answer: 1000 times
Strong acids fully ionise; weak acids partially ionise. Concentration is about amount, not strength. Each drop of 1 pH unit is 10 times more H+ ions.
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