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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