Wet reactions macro apparatus and analytical operations on

3 Wet reactions macro apparatus and analytical operations on a macro scale 

Wet reactions are carried out with dissolved substances. Such reactions lead to (a) the formation of a precipitate (b) the evolution of a gas or (c) a change of colour. The majority of reactions in qualitative analysis are carried out in solution, and details of these are given in later chapters. The following general notes on basic laboratory operations should be carefully studied. 

Equipment 1. Test-tubes the best size for general use is 15 x 2cm with 25ml total 

Beakers those of 50, 100, and 250 ml capacity and of the Griffin form are the most useful in qualitative analysis. Clock glasses of the appropriate size should be provided. For evaporations and chemical reactions which are likely to become vigorous, the clock glass should be supported on the rim of the beaker by means of V-shaped glass rods. 

Conical or Erlenmeyer flasks these should be of 50, 100, and 250 ml capacity, and are useful for decompositions and evaporations. The introduction of a funnel, whose stem has been cut off, prevents loss of liquid through the neck of the flask and permits the escape of steam. 

---