K+O₂=K₂O
M K=39g (1mol K=39g)
M K₂O=39*2+16=78+16=94 (1 mol K₂O= 94g)
1 mol K.........39 g
0.2 K............x g
x= 39*0.2= 7.8 g K
39/7.8=94/x => x= 7.8*94/39 = 18.8g K₂O
1 mol K₂O......... 94 g
x moli K₂O........ 18.8 g
1/x=94/18.8 => x= 18.8/94 = 0.2 moli K₂O.