mp g 710g
2NaNO3 + H2SO4 --> Na2SO4 + 2HNO3
2x108 142
=> mp = 2x108x71/142 = 1080 g NaNO3
1080 g NaNO3 ............................... 78% puri
m.ip ................................................. 100% impuri
= 1384,6 g NaNO3 impura
sau p% = mpx100/m.ip
=> m.ip = mpx100/p%
= 1080x100/78 = 1384,6 g NaNO3 impure
