Question

calculati cantitatea deSdin 15g PbS

Answer 1

M(PbS)=207+32=239 g/mol
M(S)=32 g/mol
facem proportie
in 239 g de PbS se contin 32 g S
in 15 g de PbS se contin x g S
x=15*32/239 = 2 g
deci m(S) = 2 g