6 g Mg impur ............. 100%
m g ............................ 90%
= 5,4 g Mg pur
5,4 g md g n moli
Mg + 2HNO3 --> Mg(NO3)2 + H2
27 2x63 1
=> md = 2x63x5,4/27 = 25,2 g HNO3
stim ca c% = mdx100/ms
=> ms = mdx100/c%
= 25,2x100/15 = 168 g sol. HNO3
=> n = 5,4x1/27 = 0,2 moli H2 degajat