Acids produce H+ ions and bases produce OH- ions in aqueous solution.
Strong acid and bases have complete dissociation. Weak acid and bases have partial dissociation, often forms an equilibrium between the OH- ions and the base itself.
The reaction with water causes the final result to change the pH value. This is due to release of Hydrogen ion and hydroxide ion from the acid and base respectively.
Electricity conductivity of a solution depends on the concentration of mobile ions. Strong acids and strong bases will therefore show higher conductivity than weak acid and bases. This can be measured using a conductivity probe.
8.3.2 State whether a given acid or base is strong or weak
Strong acids include Hydrochloric acid, Nitric acid and Sulphuric acid
Strong bases include Lithium hydroxide, Sodium hydroxide, Potassium hydroxide and Barium hydroxide
Weak acids include Ethanoic acid, Carbonic acid and Phosphoric acid
Weak bases include Ammonia and Ethylamine
8.3.3 Distinguish between strong and weak acids and bases, and determine the relative strengths of acids and bases, using experimental data
Electrical conductivity of a solution as mentioned above depends on the availability of hydrogen ions. This can be measured using a conductivity meter.
The reactions of acids described depends on the concentration of hydrogen ions. They will therefore happen at a faster rate with stronger acids. This may be an important consideration, for example, regarding safety in the labouratory, but usually does not provide an easy means of quantifying data to distinguish between weak and strong acids.
As we will learn in the next section, the pH scale is a measure of the hydrogen ions concentration and so can be used directly to compare the strengths of acids. It is a scale in which the higher the hydrogen ion concentration, the lower the pH value.
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