What have you learnt?

What have you learnt ? Let us Recapitulate

  • Many things in everyday life are consumed in liquid form.
  • A mixture of two or more substances is called a solution. The component present in smaller proportion is called a solute. The component present in larger proportion is called a solvent.
  • A solution is a homogeneous mixture of solute and solvent. Formation of a solution is a physical change.
  • Solutions having water as a solvent are called aqueous solutions. Those which have solvent other than water are called non–aqueous solutions.
  • Solutions can be classified on the basis of physical state of the solute and solvent. So there are seven possible types of solutions.
  • Arrhenius, in 1887, put forth his theory of electrolytic dissociation stating that electrovalent compounds are made of ‘Cations’ and anions. When dissolved in water, they split into positive and negative ions.
  • Acid is defined as a hydrogen containing compound which liberates H+ ions in water. Alkali is defined as a hydroxyl compound which liberates OH− ions in water. A base is a compound which                                     reacts with acid to form salt.
  • The reaction between acid and alkali ( or base ) is called neutralization reaction.
  • An acid or base which dissociates in water to a large extent is called a strong acid or base . For example, HCl, NaOH
  • An acid or base which dissociates in water to a small extent is called a weak acid or base . For example, HCN, NH4OH
  • The number of replaceable H+ ions in one molecule of an acid is called the basicity of the acid. The number of replaceable OH− ions in one molecule of an alkali ( or base )is called the acidity of the base.
  • Equivalent weight of the acid = Molecular weight / acidity of the base. Equivalent weight of the base = Molecular weight / basicity of the acid
  • There are different methods of expressing the concentration of a solution. Some of them are –mass percent, ppm, molarity, molality, normality.
  • Normality is inversely proportional to the volume of the given solution. Hence for the acid –base reaction, the equation N1V1 = N2V2 holds true. So also, strength of solution in grams per liter = normality × equivalent weight.

 

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