Question

Calculate the mass of aluminium needed to react with 50 g of cr2o3

Answer 1

2Al + Cr₂O₃ → Al₂O₃ + 2Cr

$n(Cr2O3)=\frac{m}{M}=\frac{50}{151.989}=0.32897$

find n(Al):

$\frac{x}{2}=\frac{0.32897}{1}$

x=0.6579

$m=n\times M=0.6579\times26.9815=17.75$ g