Step Up Chemistry

The conductivity of an electrolyte depends on the following factors: (a)  Nature of electrolyte - (i) Weak or Strong electrolyte- A weak electrolyte furnishes fewer ions therefore it has lower conductivity than a strong electrolyte. (ii) Valency of the ions- The ions with higher valency carry more charge and therefore they conduct more charge than the ion of lower valency. (iii) Speed of the ion- The ion which can move faster will carry the charge also faster and therefore has more conducting power. (b)  Temperature - Conductivity of an electrolyte inncreases by 2-3% for each degree rise in temperature. (c)  Concentration - When the solution is diluted the number of ions per cubic centimetre decreases, hence conductivity decreases.  Conductivity decreases with decrease in concentration both, for weak and strong electrolytes.

The word 'acid' comes from a Latin word 'acidus', which means 'sour'. Acids have a sour taste whereas bases are bitter in taste. It is not safe to taste every substance to find out if it is acidic or basic. There are some special substances that have different colours in acidic and basic mediums. They are called acid- base indicators. They can be used to test if a substance is acidic or basic. In the laboratory, two types of litmus papers are available- blue and red. These are used to test acids and bases respectively. An acid turns blue litmus red. A base turns red litmus blue.

It is found that 1 g atom of any substance contains the same number of atoms and 1 g molecule of any substance contains the same number of molecules. This number is found to be 6.022× 10^23 and is known as Avogadro's number. Avogadro's number is represented by Na.   A  mole  is a chemist's unit of counting particles such as atoms, molecules, ions, etc. which represents a value of 6.022×10^23 just as a dozen for 12, etc. are used to count different objects.  A mole of hydrogen atoms means 6.022×10^23 atoms of hydrogen whereas a mole of hydrogen molecule means 6.022×10^23 molecules of hydrogen or 2×6.022×10^23 atoms of hydrogen. A mole of oxygen molecule means 6.022×10^23 molecules of oxygen or 2×6.022×10^23 atoms of oxygen.    A mole is defined as the amount of substance which has mass equal to its gram atomic mass if the substance is atomic or gram molecular mass if the substance is molecular. 1 mole of carbon atoms= 12 grams  1 mole of oxygen atom= 16 grams