The pressure of the atmosphere Boiling point is defined as when the vapor pressure of the liquid equals to the atmospheric pressure then it starts to boil that temperature is called boiling point.
The main difference between concentration and density is that concentration refers to how much of a substance is present in a mixture, whereas density refers to the mass of a substance per unit volume.
Answer is: because weak acids do not dissociate completely.
The strength of an Arrhenius
acid determines percentage of ionization of acid and the number of H⁺ ions formed. <span>
Strong acids completely ionize in water and give large amount ofhydrogen ions (H</span>⁺), so we use only one arrow, because reaction goes in one direction and there no molecules of acid in solution.
For example hydrochloric acid: HCl(aq) → H⁺(aq) + Cl⁻(aq).
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Weak acid partially ionize in water
and give only a few hydrogen ions (H</span>⁺), in the solution there molecules of acid and ions.
For example cyanide acid: HCN(aq) ⇄ H⁺(aq)
+ CN⁻(aq).