Lead Nitrate 39 



If a white precipitate of lead sulfate is pres- 

 ent the mixture must be filterd to remove the 

 lead sulfate. Heat the filtrate, or the clear 

 solution, in case filtration was not necessary, 

 until it is saturated; then either cool the 

 solution rapidly or allow it to stand until the 

 next exercise. The lead nitrate crystals may 

 be filterd on an ordinary filter or on a Witt 

 plate and dried in the open air. If the amount 

 of mother-liquor (filtrate) is considerable 

 more crystals may be obtaind by continuing 

 the evaporation of the liquid. / 



NOTES \ 



It is essential that the apparatus be 

 clean. If sulfates are introduced by means 

 of the measuring cylinders or beakers 

 white insoluble lead sulfate will be formd 

 which must be filterd out. If commercial 

 nitric acid is used it may contain sulfuric acid. 



If the litharge does not all dissolv more 

 nitric acid may be added or the solution may 

 be filterd and the excess litharge discarded. 

 An excess of nitrate ions from the acid re- 

 duces the solubility of the lead nitrate in 

 water so it is difficult to use solubility tables 

 to determin the least volume of liquid neces- 

 sary to hold the amount of lead nitrate pro- 

 duced in solution. 



The amount of lead nitrate in 100 cc. of a 



