For example, zinc carbonate is placed in hydrochloric acid to produce zinc chloride, water and carbon dioxide gas.
Again, the salt formed is dependent on the cat ion (positively charged ion) present in the carbonate compound and an ion (negatively charged ion) present in the acid. For example; zinc ions are the cat ions while chloride ions are the anions. The two combine to form zinc chloride
Zinc carbonate + hydrochloric acid zinc chloride + water + carbon dioxide.
ZnCO3 + 2 Hcl Zncl2 + H2O + CO2
Zn + 2cl zncl2
ZnCO3 + H2SO4 ZnCO3 + H2O + CO2
ZNCO3 + H2C2O4 ZNC2O4 + H2O + CO2
The carbon dioxide and water are formed when hydrogen ions, present in the aqueous acid solutions react with carbonate ions.
2 H+ + CO3 2- H2O + CO2
From the above, it is clear that all aqueous acids contain hydrogen ions. ie
Hcl (aq) H+ (aq) + CL-(aq)
H2SO4 H+ + SO4 2-
CH3COOH 2H+ + CH3COO
A strong acid is defined as one that dissociates completely in aqueous solution.
A weak acid is defined as one that dissociates partially in aqueous solution.
The pH value of a solution is related to the number of hydrogen ions present; the higher the number of the hydrogen ions present, the lower the pH value and the stronger the acid.
For example, Hydrochloric acid solution has a low pH value than ethanoic acid because it has more Hydrogen ions than ethanoic acid.
Acids whose aqueous solutions contain a high number of hydrogen ions are therefore strong, while those with few Hydrogen ions are weak acids.
Nitric V acid, hydrochloric, and sulphuric VI acid are examples of strong acids.
Ethanoic, ethanedioic and methanoic acid are examples of weak acids. When weak acids are dissolved in water, very few molecules are converted into ions; most remain in small molecules of unionized particles.