Question

What mass in grams of iron metal can be formed by the reaction of 2.14 gAI metal with excess Fe₂O₃, according to the thermite reaction: 2Al(s) + Fe₂O₃ → 2Fe(s) + Al₂O₃(s)

Answer 1

Answer:

4.43 g Fe

Explanation:

To find the mass of iron, you need to (1) convert grams Al to moles Al (via molar mass), then (2) convert moles Al to moles Fe (via mole-to-mole ratio from reaction coefficients), and then (3) convert moles Fe to grams Fe (via molar mass). It is important to arrange the conversions/ratios in a way that allows for the cancellation of units (the desired unit should be in the numerator). The final answer should have 3 sig figs because the given value (2.14) has 3 sig figs.

Molar Mass (Al): 26.982 g/mol

2 Al(s) + Fe₂O₃ --->  2 Fe(s) + Al₂O₃(s)

Molar Mass (Fe): 55.845 g/mol

 2.14 g Al           1 mole              2 moles Fe           55.845 g
----------------  x  -----------------  x  --------------------  x  ------------------  =  4.43 g Fe
                         26.982 g           2 moles Al             1 mole